Testing, testing... [Archive] - 6.5 Grendel Forum : : For the 6.5 Grendel Aficionado

stanc

06-14-2011, 07:21 PM

Okay, I'm going to take one last shot at this topic. Some people, John perhaps foremost among them, consider 6.5 Grendel capable of replacing both 5.56 and 7.62 NATO. Others, like Tony, think a slightly larger, more powerful 6.5mm cartridge will be needed, but that 6.5 Grendel could serve as a test vehicle.
http://upload.wikimedia.org/wikipedia/commons/thumb/c/ce/762_65G_556.jpg/112px-762_65G_556.jpg
It is my position that there is insufficient data to confirm either premise, and therefore shooting tests should be done. I would gladly undertake such testing myself, but no longer possess the physical ability to do so. If any Grendel shooters with requisite guns and ammo would care to participate, following are the tests I'd like to see done, and results posted in this thread.

P.S. Please do not waste thread space by posting objections to the proposed tests. If anybody would prefer to do other tests, please feel free to do them and report the results.

stanc

06-14-2011, 07:22 PM

Goal: Compare hit probability using service grade weapons and ammunition.

Use identically-configured, 14.5" (or 16") barrel, M4-type carbines in 5.56mm and 6.5mm, with same type of sights.

One target, any range 500 yards/meters to 1000 yards/meters. Use prone or (vehicle) supported position.

20 rounds slow fire. Record number of hits for each weapon.

Ammunition
5.56 NATO 62gr M855
6.5 Grendel 110gr Wolf FMJ or 120gr Wolf MPT (or handloads w/Norma 120gr FMJ)

stanc

06-14-2011, 07:23 PM

Goal: Compare hit probability using match grade weapons and ammunition.

Use identically-configured, 20" barrel, SASS/SDMR-type rifles* in 5.56mm, 6.5mm, and 7.62mm, with same type of sights.

One target, any range 500 yards/meters to 1000 yards/meters. Use prone or (vehicle) supported position.

20 rounds slow fire. Record number of hits for each weapon.

Ammunition
5.56 NATO 77gr Mk262
.264 LBC 123gr SMK (or 6.5 Grendel handloads w/123gr SMK)
7.62 NATO M118LR or Mk316 or Federal GMM w/175gr SMK

* http://en.wikipedia.org/wiki/M110_Semi-Automatic_Sniper_System
* http://en.wikipedia.org/wiki/United_States_Army_Squad_Designated_Marksman_Rifle

stanc

06-14-2011, 07:26 PM

Goal: Compare barrier defeat ability using FMJ ammunition.

Use 20" barrel rifles in 6.5mm and 7.62mm.

Shoot CMU -- aka cinder block -- backed up by jugs of water (see attached drawing), at any range from 25 yards/meters to 200 yards/meters. Record number of water jugs penetrated (and photograph recovered bullets, if possible).

Ammunition
6.5 Grendel 110gr Wolf FMJ (or handloads w/Norma 120gr FMJ)
7.62 NATO 147gr M80

noone

06-15-2011, 03:01 PM

I think those tests would indeed show very interesting results. It might also be useful to test all three cartridges on ordnance gelatin by shooting the various bullets at 100 yards/meters for the infantry rifle test, 650 yards/meters for the sniper/designated marksman rifle, and 200 yards/meters for the machine gun test.

Comparing all the results would indeed provide very useful infomation.

The only other suggestion would be to use a better grade of factory ammo for the Grendel than Wolf. Wolf ammo is well known for being fairly inaccurate, and that wouldn't help the results. Hornady, Alexander Arms, or Black Hills ammo would provide more consistent accuracy. I'm not suggesting using match ammo for the Grendel and ball for the other cartridges as that wouldn't be fair. However, using ammo that is pretty well known for the worst accuracy of factory ammo isn't fair either.

Overall, I think the testing suggested is well thought out, and would be very helpful. I doubt the military will do such testing because the results may strongly suggest that a change is needed. And the military supply line has long been known for not wanting to change.

stanc

06-15-2011, 04:29 PM

I think those tests would indeed show very interesting results. It might also be useful to test all three cartridges on ordnance gelatin...
I agree. The reason I did not suggest gel tests is because very few, if any, members have the ability (or desire) to work with gelatin. I wanted to keep things as simple as possible.

The only other suggestion would be to use a better grade of factory ammo for the Grendel than Wolf. Wolf ammo is well known for being fairly inaccurate, and that wouldn't help the results. Hornady, Alexander Arms, or Black Hills ammo would provide more consistent accuracy. I'm not suggesting using match ammo for the Grendel and ball for the other cartridges as that wouldn't be fair. However, using ammo that is pretty well known for the worst accuracy of factory ammo isn't fair either.
The trouble is, Hornady, AA and BH make premium 6.5 hunting and target ammo. They do not make 6.5 FMJ, or ammo that is representative of service grade ball in terms of accuracy.

I specified Wolf because (from what I recall posted by LR1955 on the old forum) the MPT is comparable to standard military ball in regard to accuracy, and the pending FMJ is the same bullet type.

However, a possible answer to your "fairness" objection would be to use ammo with TSX bullets for the infantry rifle and machine gun tests. That should provide the same degree of accuracy in each caliber for the infantry rifle test, and give representative penetration of each caliber in the machine gun tests. In factory ammo, Black Hills makes 62gr 5.56 TSX, AA has 120gr 6.5 TSX, and Federal offers 150gr 7.62 TSX. Would that be satisfactory?

LR1955

06-15-2011, 07:24 PM

stanc

06-15-2011, 09:25 PM

Since you are talking service grade rifles / carbines -- best state that the Grendel must be service grade too.

Weight and length limitations are also part of the requirements and should be stated.
Gene, I attempted too do that by writing:

"Use identically-configured, 20" barrel, M16-type rifles or 14.5" (or 16") barrel, M4-type carbines in 5.56mm and 6.5mm, with same type of sights."

LR1955

06-16-2011, 01:12 PM

Use identically-configured, 20" barrel, M16-type rifles or 14.5" (or 16") barrel, M4-type carbines in 5.56mm and 6.5mm, with same type of sights.

Three targets, widely spaced, at any range from 25 yards/meters to 500 yards/meters. Use standing position at close range(s), kneeling, prone, or (vehicle) supported position for long range(s).

30 rounds, firing controlled pairs (aka double taps), in timed fire, using same time limit for each. Determine number of hits for each weapon.

Ammunition
5.56 NATO 62gr M855
6.5 Grendel 110gr Wolf FMJ or 120gr Wolf MPT (or handloads w/Norma 120gr FMJ)

Stan:

Easy one for me to do.

Just a few questions.

What is it you are trying to prove or disprove? My suggestion is that if you don't want to state your objectives in the open that you write them down and send them to a honest third party. Once they are written and sent, you can not change them. I trust Waites so given you can answer a few more questions about this portion of your test, I may be tempted to run it if Waites had a copy of your research question and agreed that the question was clearly stated and without prejudice towards any single cartridge or weapon.

As for other questions. SASS and SDMR are only names. What specific technology do these possess that other rifles don't? I have many rifles but am not sure if there is some technology unique to a SASS or SDMR that my other rifles don't have. You specified SASS and SDMR so define them so I can tell if I have the same technology in my rifles.

BTW -- what is the issued US Army SDM rifle? I have not seen one in the hands of an Infantryman -- ever. Unless you are talking about that M-14 retread.

State the specific size and shape of the target.

What type of target material? Steel is unreliable at distance so paper should be used.

Define a hit? If it is anywere on the paper or must be in a kill zone of some size. If a kill zone -- specify its location and dimensions. This makes a difference in how much attention one focuses and how one approaches the environment when shooting.

What specific distances? Sorry but you have to be specific in the distances as again, how a shooter approaches the situation depends on distances.

What is your time limit for the 20 rounds slow fire?

Under what environmental conditions would you consider the test to be valid?

LR1955

stanc

06-17-2011, 01:08 PM

Stan: What is it you are trying to prove or disprove?
Gene, I stated that in post #1. For years we've discussed the idea that 6.5 Grendel has good enough performance to replace 5.56 and 7.62 NATO. I'd like to see some test data that either validates or negates the theory.

As for other questions. SASS and SDMR are only names. What specific technology do these possess that other rifles don't? You specified SASS and SDMR so define them so I can tell if I have the same technology in my rifles.
In post #3 I provided links to descriptions of the SASS and SDMR. If you want more detailed info, I don't have it.

State the specific size and shape of the target.
Head and torso silhouette. Exact type doesn't matter.

What type of target material? Steel is unreliable at distance so paper should be used.
Okay.

Define a hit? If it is anywere on the paper or must be in a kill zone of some size.
Anywhere on the target.

What specific distances? Sorry but you have to be specific in the distances as again, how a shooter approaches the situation depends on distances.
I didn't list a specific distance, because not all shooters will have access to 1000-yard firing ranges.

What is your time limit for the 20 rounds slow fire?
I'd think that would depend on the distance to the target. Whatever is appropriate, as long as it's the same for each caliber.

Under what environmental conditions would you consider the test to be valid?
Under any environmental conditions that you feel like shooting in.

P.S. I've revised post #2, the infantry rifle comparison, and added the purpose of each test to posts #2-4.

JASmith

06-17-2011, 03:06 PM

Comparing the 5.56 M855 at ranges of 500 meters and beyond with 14.5" barrel weapons seems to bias the test in favor of the Grendel.

Where is the testing for barrier defeat when the pucker factor gets high? E. g. the truck door or windshield at ranges of 50 meters and less?

I'm in concert with LR1955 -- your test protocol must meet some significant standards to be taken seriously.

stanc

06-17-2011, 04:46 PM

Comparing the 5.56 M855 at ranges of 500 meters and beyond with 14.5" barrel weapons seems to bias the test in favor of the Grendel.
How? The M4 carbine is the current standard individual weapon in the US Army. If 6.5 Grendel were adopted to convert existing 5.56mm weapons, it is reasonable to think that the barrel length would be kept at 14.5 inches. Ergo, compare at that length.

Where is the testing for barrier defeat when the pucker factor gets high? E. g. the truck door or windshield at ranges of 50 meters and less?
The truck door and windshield tests need to be done with ordnance gelatin in order to provide useful information. I figure that no members (with the possible exception of Bill Alexander and Gary Roberts) are likely to want to cope with performing gel tests. Cinder block penetration, OTOH, is very simple to test, and can be done by anybody fit enough to carry and emplace the block and water jugs.

I'm in concert with LR1955 -- your test protocol must meet some significant standards to be taken seriously.
As LR1955 would say, define significant standards. :p ;)

Joe, this isn't intended to duplicate military acceptance testing. All I'm proposing are some informal comparison tests to evaluate if there's any substance to the theory that 6.5 Grendel is good enough to replace 5.56 and 7.62 NATO.

If the results should show results that support the theory, then at that point planning for more rigorous testing could be done. OTOH, if the results don't support the theory, then why bother spending the time to devise more complex (and expensive) tests?

JASmith

06-17-2011, 05:32 PM

How? The M4 carbine is the current standard individual weapon in the US Army. If 6.5 Grendel were adopted to convert existing 5.56mm weapons, it is reasonable to think that the barrel length would be kept at 14.5 inches. Ergo, compare at that length.
The range is the hiccup. Remember that most folks carrying M-4's have a far greater chance of engaging targets well under 300 meters. One would think that relevant testing at these shorter ranges is in order.

Accuracy isn't the principal issue for these shorter range tests, but bullet performance is.

The truck door and windshield tests need to be done with ordnance gelatin in order to provide useful information.
The spirit of the test regime, especially with the cinder block and milk jug protocol, suggests that plywood and water jugs could readily be used behind something that resembles a windshield or door frame.

For example, the door frame test specifies an air gap between the gel block and the barrier. We could readily use a 3/8" wafer board backed by, say, two milk jugs, followed by perhaps a 10" air gap and then a second wafer board as a witness plate. The second air gap is to keep the witness plate from being disrupted by the splash from the milk jug. Twenty gauge steel sheet could be substituted for the wafer board if you want a more visible hole.

As LR1955 would say, define significant standards...this isn't intended to duplicate military acceptance testing.
While no amount of testing by us amateurs can hope to duplicate, let alone supersede, formal military acceptance testing, poorly defined and designed tests can do an awful lot of harm.

Remember, our goal is to encourage analysis and testing by the service acquisition community.

We need to posit a hypothesis like "The 6.5 Grendel can replace both the 5.56 and 7.62 mm NATO ammunition types." and then build the analytical case that shows that, given demonstrated ammunition performance, the hypothesis is proven. Then the tests we define and execute will have the impact they need.

I would also submit that the example hypothesis is far too weak to gain traction even with the most zealous congressman. Extending earlier posts by LR1955 about necessary performance improvements, we have to show essential equivalence in every category except those where the Grendel is clearly superior.

Anything less sets us up for a Pyrrhic victory.

stanc

06-17-2011, 07:05 PM

The range is the hiccup. Remember that most folks carrying M-4's have a far greater chance of engaging targets well under 300 meters. One would think that relevant testing at these shorter ranges is in order.
I agree that testing at shorter ranges is a good idea. That's why the first iteration of the Infantry Rifle test called for target distances as close as 25 yards. However, hit probability of any assault rifle cartridge -- especially the low-recoil 5.56x45 -- will be good at close range.

I changed the range requirement to longer distances, primarily because of the reported complaints from troops in Afghanistan that 5.56 lacked sufficient reach to engage an enemy who 50% of the time attacks from as far away as 1000 yards. I think it's more important to determine if 6.5 Grendel would answer that complaint, and if so, how well.

Accuracy isn't the principal issue for these shorter range tests, but bullet performance is.
Concur. But, we don't have access to 5.56 M855A1 ammo, and AFAIK, neither an M855-type nor an M855A1-type bullet exists for 6.5 Grendel. So what 5.56 and 6.5 loads would you use to compare terminal performance?

The spirit of the test regime, especially with the cinder block and milk jug protocol, suggests that plywood and water jugs could readily be used behind something that resembles a windshield or door frame.
True. And there are other "witness pack" possibilities, as shown in a couple of NDIA presentations by Gandy and Arvidsson. But, again -- what 5.56 and 6.5 loads would you use to compare terminal performance?

While no amount of testing by us amateurs can hope to duplicate, let alone supersede, formal military acceptance testing, poorly defined and designed tests can do an awful lot of harm.
Well, if you consider my proposed tests to be poorly designed, then propose some of your own.

Remember, our goal is to encourage analysis and testing by the service acquisition community.
Agreed.

We need to posit a hypothesis like "The 6.5 Grendel can replace both the 5.56 and 7.62 mm NATO ammunition types." and then build the analytical case that shows that, given demonstrated ammunition performance, the hypothesis is proven.
Yes, but to date all we have is theory and supposition behind that hypothesis. There needs to be empirical evidence, which can only be had via testing.

JASmith

06-17-2011, 07:41 PM

I would use the same ammunition you propose to use for the cinder block/milk jug "Machine Gun" test. Remember that all we need to do is best the 147 gr 7.62 round. Hence we don't need 5.56 NATO for this test.

We are, for the most part, all in agreement that the Grendel would do as well as either the 5.56 or the 7.62 NATO in dismounted infantry roles. The point that LR1955 makes is that positing the Grendel as merely being able to replace the 5.56 and 7.62 won't cause it to happen. He is right on the money. We have to identify at least one or two areas where the Grendel is far superior and assure ourselves that it does at least as well in all the other categories.

The hypothesis has to be far stronger and be supportable by analysis and testing.

Let's make sure the testing we do in the near future helps demonstrate Grendel superiority.

stanc

06-17-2011, 08:20 PM

I would use the same ammunition you propose to use for the cinder block/milk jug "Machine Gun" test. Remember that all we need to do is best the 147 gr 7.62 round. Hence we don't need 5.56 NATO for this test.
Okay, you're confusing me. Now you say that you don't want to test 5.56mm terminal effects. However, in your two previous posts you objected to my proposed test with the 5.56mm M4 carbine on the grounds that "Accuracy isn't the principal issue for [the M4], but bullet performance is." :confused:

We are, for the most part, all in agreement that the Grendel would do as well as either the 5.56 or the 7.62 NATO in dismounted infantry roles.
Again, that's the theory...but where is the test data that confirms it?

The hypothesis has to be far stronger and be supportable by analysis and testing.
I don't care how strong you make the hypothesis, testing needs to be done before there is anything to analyze.

Let's make sure the testing we do in the near future helps demonstrate Grendel superiority.
Whoa! And you accused me of bias???

I want "fair and balanced" tests. If the results show 6.5 Grendel is actually the superior choice, that's great. If they don't, dems da breaks. I wouldn't want "tests" designed to make 6.5 Grendel only appear to be superior.

JASmith

06-17-2011, 08:45 PM

No confusion -- If Grendel is better in terminal effects than 7.62X51 then it will be better than 5.56. Hence this and the cinder block test don't need 5.56.

I don't claim Grendel superiority. I maintain that we need to prove the Grendel is clearly superior in at least one key area to get traction in the quest.

Proving that it is merely "as good as" guarantees that nothing happens...

The tests do indeed need to be fair and balanced -- but if the results show that the Grendel is about the same as the 7.62 and 5.56 in all areas, then you're done and we'll continue with the current weapons mix.

stanc

06-17-2011, 09:26 PM

No confusion -- If Grendel is better in terminal effects than 7.62X51 then it will be better than 5.56. Hence this and the cinder block test don't need 5.56.
I agree that cinder block penetration only needs to be done with 6.5 and 7.62, since that barrier is more likely to be hit by MMG fire, and the deficiency of 5.56 in that regard was noted almost two decades ago in Somalia.

However, I've seen no complaints about 7.62 in defeating truck doors and windshield glass, and at the close range you cited, it's highly unlikely that a 110gr 6.5 FMJ @ 2500 fps will prove superior to a 147gr 7.62 FMJ @ 2800 fps.

IMO, trying to compare 6.5 vs 7.62 at close distances virtually guarantees that 6.5 will come off second best. As evidence of that, the only 6.5 FMJ gel test we currently have shows a wound profile inferior to that of non-fragmenting 7.62 FMJ.

As a consequence, it seems to me that for comparisons of close-range terminal effectiveness, it'll be necessary to do 6.5 vs 5.56, which can't be done "apples-to-apples" with the 5.56 M855 or M855A1. The best that could be done is a relative comparison of 6.5 110gr (or 120gr) lead-core FMJ vs 5.56 62gr lead-core FMJ, which may be of little value in presenting the case.

The tests do indeed need to be fair and balanced -- but if the results show that the Grendel is about the same as the 7.62 and 5.56 in all areas, then you're done and we'll continue with the current weapons mix.
Yes. What I think need be done is to show 6.5 is significantly better than 5.56, but only comparable to 7.62, not necessarily better. There is no chance of 6.5 Grendel officially replacing 7.62 NATO. The best that could be hoped for is to replace 5.56 NATO, and then -- because of its range capability and relatively light weight -- be used in lieu of 7.62 in the field.

Bill Alexander

06-18-2011, 01:21 AM

Unless orchestrated correctly with well balanced loads the protocol of examining a caliber against another is a fools errand. Randomly picking a loading simply because it is an FMJ without any thought as to load development and bullet construction will at best misrepresent the capability of that caliber. The Wolf 110 will not be optimized for a military type range of targets but rather will be considered in the light of economical development and production. Equally the 120 Norma is in basis a hunting projectile for pelt and bird in Europe not a military construction.

Just as it was not possible to quickly and cheaply rig high capacity magazines with string and gum, it was expounded that the Grendel could never offer such capability, so we have argued that the same gum and gaffer tape approach must preclude its ability to operate from a belt. The case was made that it could not be pounded into an existing link on an existing feed tray. This morphs in the internet from a simple consideration into what looks like and exhaustive engineering study and when cursory reviewed by interested parties such information works heavily against us.

In this same approach what would be the interest in running commercial bullets in handloads against well established military calibers. We are at present undertaking to build T3 technology into the Grendel, a 6.5mm M855A1 if you will. Balance this loading into a SAFE cartridge which will offer weapon durability and you now have the basis of a simple study. Our apples to apples of military constructions is met and we have but to throw these from similar barrel lengths to start the examination.

Tony Williams

06-18-2011, 09:38 AM

LR1955

06-18-2011, 01:04 PM

While I laud the motivation for carrying out such testing, I must draw attention to the recent ARDEC calibre study which may make it unnecessary.

The Army is keeping very quiet about this, but according to the info I am picking up, they did a thorough job. 5.6, 6.2, 6.5, 7.0 and 7.8mm projectiles were tested, each in two bullet styles (Barnes TSX and a "GP" bullet similar in design to M855A1 EPR) ranging in weights from 61 for the 5.6mm to 165 for the 7.8mm. MV and ME varied by calibre. Shooting tests included Angle of Attack (yaw) at 50m and 300m and barrier and post barrier penetration in 20% ordnance gel using many of the FBI test targets (Level IIIA vest, glass, concrete, steel plate) and the 2005 JWB-IPT protocol. An analysis was then done with the raw data of EKE (Kinetic Energy), Pi/Pi/h versus weight, cost, felt recoil, etc. High speed photos were captured of all shots as were images of the bullet fragments. Finite Element Simulations were then developed for expected performance out to 600m (the expected maximum range for future rifle fire).

The 6.5 and 7.0 performance was superior across the board with the exception of Stowed Kills, which is always slanted towards the smaller, lighter calibres.

So it seems that the technical argument has been won. The problem will be to get the Army to act on its own findings. The message seems to have been acknowledged at least to some extent, since future LSAT development will be aimed at delivering improved long-range performance over any 5.56mm loading. Intermediate calibres are now to be examined by the LSAT team, but it would obviously be much quicker and cheaper to resolve the optimum calibre/ballistics/bullet type using conventional ammo and gun techology before redesigning LSAT (and preferably with Geneva-compliant bullets as a part of the development).

It is also important to bear in mind that there are three separate reasons for adopting an intermediate calibre:

1. To improve on the terminal effectiveness, barrier penetration and long-range ballistics of the 5.56mm.

2. To match the long-range ballistics of the 7.62mm with significantly less ammo weight and recoil.

3. To save on procurement, training and support costs by fielding only one calibre and weapon range in portable small arms rather than two.

Our focus tends to be on the first two of these, but I suspect that it's the third one which will prove to be the strongest argument (although of course, it only applies if the first two can be achieved).

Tony / Guys:

You said you found this out which means you have a copy of the ARDEC report or can send a link or means of obtaining the report.

Not that the findings you state are earth shattering. We stopped using the .308 competitively many years ago when the bullet industry started making a bigger variety of 6.5mm match grade bullets than .308. Lighter recoil, equal or significantly better ballistics to 1000 yards, and for .308 based 6.5mm cartridges -- equal barrel life. Lighter recoil probably played as much a role as a decent selection of match grade bullets. Although the improvement in accuracy was probably not significant, the reduction in recoil most certainly was and this meant higher scores.

The 7mm never caught on as it really wasn't that much different in recoil from a .308 and only had one or two types of match grade bullets available.

I can already predict the outcome for Stan though.

His CQM controlled pair test would show the 5.56 to hold a significant advantage.

The mythical DMR test (there is no issued 5.56 DMR for the conventional side), 550 meters is the effective range. Why 550 meters? Maybe the KD range the AMU owns probably doesn't have a 500 yard line? Or they figured that in order for their DMR idea to get traction it needed to show a improvement over the 500 yard (460 meter) max effective range of the issued carbine / M-16A2. Most likely because their KD range is made in yards and not meters and they had to show a improvement. Either way, given a rifle made with the same features as the non existent DMR, the results would not show significance.

Comparing a 20 inch barrel Grendel firing one of the match grade bullets to a 110 firing M-118 Long Range -- both would be statistically equal in terms of hit on a E-Sil at 800 meters (again the max effective range on a point target for a US SWS). I predict that 118 would out shoot the Grendel past 800 and at 1000 the difference would be enough to determine significance.

As for the cinder block test -- it will take less rounds of M-80 to destroy that cinder block than Grendel simply due to kinetic energy differences. Not sure if the advantage would be significant as I am not sure what the test was intended to prove or disprove.

LR1955

Tony Williams

06-18-2011, 01:22 PM

Tony / Guys:

You said you found this out which means you have a copy of the ARDEC report or can send a link or means of obtaining the report.

No, I haven't and I can't. AFAIK the report has not been released to anyone. But ARDEC gave a presentation about it at the annual Ammunition Initiatives Meeting III (AIM III) of the Technical Support Working Group a couple of months ago. I wasn't there (it was by invitation only) but news of the presentation has been filtering out which is how I have learned about it.

I gather that it created quite an impact, especially in the light of the current carbine competition. There was some criticism of the carbine competition on the grounds that there was no point in going to such a huge amount of trouble to select a new 5.56mm carbine when the army's own research showed that this was not the way to go. Which may be why the Army hasn't released the report...

stanc

06-18-2011, 04:03 PM

stanc

06-18-2011, 06:04 PM

The mythical DMR test...
Are you saying that the SDMR was never built or fielded?

As for the cinder block test -- it will take less rounds of M-80 to destroy that cinder block than Grendel simply due to kinetic energy differences. Not sure if the advantage would be significant as I am not sure what the test was intended to prove or disprove.
It was not intended to "prove or disprove" anything. It was a quest for information, to see how 6.5 Grendel barrier penetration compares to that of 7.62 M80.

However, I just remembered there was a FutureWeapons episode in which a cinder block was shot with 6.5 Grendel (see 2:30-2:45 of http://www.youtube.com/watch?v=haqXE8nq3io ), and result was virtually the same as I got with 7.62 M80 some years ago.

JASmith

06-18-2011, 06:17 PM

...they did a thorough job. 5.6, 6.2, 6.5, 7.0 and 7.8mm projectiles were tested, each in two bullet styles (Barnes TSX and a "GP" bullet similar in design to M855A1 EPR) ranging in weights from 61 for the 5.6mm to 165 for the 7.8mm.
Tony,

I did a quick check and, if one keeps the same shape, 61 grain 5.6 bullet will scale to a 165 grain 7.8 bullet. (It works out to about 160 gr if one scales from .224 to .308 in.)

I conclude from this that they likely attempted to make the test protocol "fair and even" by maintaining the same shape of bullet throughout the test. We know that the 61 grain bullet is less effective than the 77 grain bullet in 5.6. We also know that the 165 grain 7.8 bullet gives up a lot in muzzle velocity when used in the 7.62X51 NATO.

Small surprise that the results favor the middle ground.

These tests may be definitive for those pursuing an already identified caliber and cartridge, but other tests have a good chance of having a different caliber coming out on top. This is especially true if one includes cartridge diameter and length as part of the test protocol, e. g., a cartridge based on the PPC for the 5.6 gives a significant velocity boost for the longer, heavier lead-free bullets even in the short action, the same is true for BR-based cartridges for 6 and 6.5 mm. Going to the 7.62X51 overall length and using smaller diameter cartridges would also give more latitude for the 6.5 & 7 mm diameters to show well.

It would be interesting to see what weight of bullet was actually used for the 6.5 -- scaling as inferred above would yield 95-100 grains. This could be a very interesting weight class for the Grendel.

LR1955

06-18-2011, 08:59 PM

Are you saying that the SDMR was never built or fielded?

It was not intended to "prove or disprove" anything. It was a quest for information, to see how 6.5 Grendel barrier penetration compares to that of 7.62 M80.

However, I just remembered there was a FutureWeapons episode in which a cinder block was shot with 6.5 Grendel (see 2:30-2:45 of http://www.youtube.com/watch?v=haqXE8nq3io ), and result was virtually the same as I got with 7.62 M80 some years ago.

Stan:

The AMU made a few of these rifles for 3rd ID and maybe the 82nd about seven or eight years ago when the SDM thing was of more interest than today. From my recollection based on communications with the Commander, USAMU at the time, the rifles had to be M-16A4's so if your unit didn't have A-4's it was a automatic No - Go.

The AMU had to stop the effort due to issues concerning the color of the money based on FORSCOM vs USAREC budgetary regulations and some regulations involving exactly what could be done to a TOE issued rifle and what couldn't -- and by whom. The AMU had the regulatory authority to do the transformation but apparently not to do it for anyone except the AMU and not with TOE property of any other unit.

No one got into serious trouble but it ended that part of the DMR. I believe some money was dedicated to it but have not seen a 5.56 DMR issued to any of the SBCT's I have worked with over the years. I have seen the M-14 DMR rifle issued, though.

As for a test. It either supports or does not support a hypothesis. As you said, you wanted to compare. In most cases it would either exceed or not exceed, but in some it may be of importance to determine if they equaled too. Hence getting beaten up over a research question. And, you must state a significance level before you run your tests or your credibility as a researcher will be absolutely trashed. Hence getting beaten up over not stating a level of significance.

LR1955

stanc

06-18-2011, 10:28 PM

Stan: As for a test. It either supports or does not support a hypothesis. And, you must state a significance level before you run your tests or your credibility as a researcher will be absolutely trashed.
Gene, that's sheer nonsense. If you have several different brands of factory ammo that you want to chronograph, do you establish signicance levels just to measure and record the velocities? Well, maybe you do ;) , but everyone else just goes to the range and chrono's the ammo.

As far as I'm concerned, you and Joe have been giving me a load of grief for the wrong reason. The two of you seem to be equating research to collect data and writing a requirements document. The latter needs to have significance levels; the former does not.

Well, no matter. I've tried my best to propose objective tests (both here and on 68forums), and give fair and balanced analysis in my magazine articles, but all I get are complaints that I'm unfair and biased...and need to implement significance levels. :rolleyes: I've finally reached the point where I'm tired of it and just don't care anymore. Do the proposed tests, or don't do them, as you wish.

Stan

Tony Williams

06-19-2011, 07:40 AM

http://farm4.static.flickr.com/3340/3519464264_5242fa4d79.jpg
Thanks for sharing. :cool:
I remember that show...and a goofy young Goldie Hawn...and Judy Carne! :p

How is "Stowed Kills" defined? That statement makes it sound as if it is just the number of rounds in the magazine, without taking into account the per-round effectiveness?

Some more details I have picked up:

The calibres were tested for penetration, terminal effects, accuracy, initial, retained and striking energy, wind drift, etc. and calculations were made for stowed kills, recoil impulse and various other metrics.

.224 calibre (5.56mm) had the greatest Probability of Incapacitation by “Stowed Kills” (due to the lighter single cartridge weight).

Larger calibre bullets inflict more target damage, and the increase in target damage is greater than the increase in system weight.

Larger calibres had superior post-barrier target effects, with .277 calibre (7.0mm) equalling .308 (7.62mm) against barriers by weight.

The calibre range between .257 (6.5mm) and .277 (7.0mm) is the optimum for overall target effects.

LR1955

06-19-2011, 12:36 PM

Some more details I have picked up:

The calibres were tested for penetration, terminal effects, accuracy, initial, retained and striking energy, wind drift, etc. and calculations were made for stowed kills, recoil impulse and various other metrics.

.224 calibre (5.56mm) had the greatest Probability of Incapacitation by “Stowed Kills” (due to the lighter single cartridge weight).

Larger calibre bullets inflict more target damage, and the increase in target damage is greater than the increase in system weight.

Larger calibres had superior post-barrier target effects, with .277 calibre (7.0mm) equalling .308 (7.62mm) against barriers by weight.

The calibre range between .257 (6.5mm) and .277 (7.0mm) is the optimum for overall target effects.

Tony et. al:

Does any of this surprise anyone? Sure doesn't surprise me. Wish ARDEC had contracted with me for the study. I would probably be a couple million richer and would not have had to shoot a single round of ammunition. Everything Tony reports has been documented or can be interpolated from scientifically proven data.

There is nothing new about gilding metal covering a steel, composite, or lead core bullet. There has been no significant improvement in bullet design since around 1920. There has been no significant improvement in powder since the 1950's. And no significant change for the better in rifle design since the 1950's. The technology is mature and unless someone comes up with a powder that can significantly increase speed while maintaining the same or lower pressures, you have what you have.

Now, some guys hate the 5.56 and have hated it blindly since it was devised. And they hated it more when it got selected to replace the 7.62 for the service rifle. Just remember that part of the reason why the 7.62 was retained was because of the same prejudice against anything other than .30 caliber. This crowd probably thought replacing the 30-06 was as destructive to mankind as the guys who thought that replacing a single shot 45-70 with a smaller cartridge would mean our defeat. Or the same who insisted on having a magazine block in a Springfield in order to keep guys from blasting without aiming. Or the same who thought a semi-automatic service rifle would mean our logistical system would break down due to ammo consumption.

Bottom line again. The testing has already been done and there really is no change in terms of ballistics and hasn't been for seventy or eighty years.

A guy still must hit the target and if nothing can be done to improve the powder or bullet design, then one turns to rifle and sighting system design. This is where you may be able to quantify any improvement that the ammunition can offer. I am amazed at how poorly the current crop of issued service carbines is in terms of ergonomics. And I believe a much better optical sighting system can be designed and made for issued carbines.

LR1955

Tony Williams

06-19-2011, 12:58 PM

Tony et. al:

Does any of this surprise anyone? Sure doesn't surprise me.

Nope. I've been arguing for a 6.5mm intermediate calibre for the last 40 years.

The testing has already been done and there really is no change in terms of ballistics and hasn't been for seventy or eighty years.

See the .276 Pedersen (late 1920s) and the .280/30 British (late 1940s).

stanc

06-19-2011, 03:50 PM

The calibres were tested for penetration, terminal effects, accuracy, initial, retained and striking energy, wind drift, etc. and calculations were made for stowed kills...
Anybody know how that calculation is made?

.224 calibre (5.56mm) had the greatest Probability of Incapacitation by “Stowed Kills” (due to the lighter single cartridge weight).
That doesn't seem logical. If it takes three hits from .224 bullets (30-rd magazine) to kill or incapacitate, but only two hits from a larger caliber (25-rd mag), wouldn't that mean .224 has fewer stowed kills? Or maybe I have the wrong idea of what "Stowed Kills" is?

Larger calibres had superior post-barrier target effects, with .277 calibre (7.0mm) equalling .308 (7.62mm) against barriers by weight.
What does "by weight" mean?

LR1955

06-19-2011, 05:17 PM

Anybody know how that calculation is made?

That doesn't seem logical. If it takes three hits from .224 bullets (30-rd magazine) to kill or incapacitate, but only two hits from a larger caliber (25-rd mag), wouldn't that mean .224 has fewer stowed kills? Or maybe I have the wrong idea of what "Stowed Kills" is?

What does "by weight" mean?

Stan:

Yes, you do have a good idea what a 'Stowed Kill' is.

Dr. Roberts discusses this among other things here. http://www.m4carbine.net/showthread.php?p=393730

See his comments about Page 26 under section 3.

This is why factors are weighed when making decisions or running a statistical analysis. Stowed Kills may not necessarily mean as much in a decision as other factors or they may mean as much or more.

LR

JASmith

06-19-2011, 06:10 PM

Gene,

Thanks for the link to Dr. Roberts' critique.

At one time I worked in an Air Force laboratory where we worked a number of research projects in competition and jointly with the other services.

The comment that "...researcher and facility in the nation DISAGREES with XXX's methodology and conclusions" can describe almost any service laboratory most, if not all, of the time. The fault is not directly in the laps of the individuals, but rather the overriding need to avoid chaos by making premature changes. One of my longstanding frustrations was that this sense of caution was over-applied. The mantra was "no change" until the new method is proven and mature.

The discussion also helps validate the need to wisely design and execute testing that will ultimately be used for advocacy. The claim will be that everything worth testing has been tested -- several times.

Our opportunity for reclama will lie in having a protocol that will stand up to a peer review (in the academic literature) and to work with the right messengers.

The "right messengers" are possibly more critical than excellent tests. These are folks who, when convinced of the value of a new idea, can influence folks who control money in industry and government. They can take our test results and coarse analyses to the right folks and give the system a chance.

stanc

06-19-2011, 10:51 PM

Unless orchestrated correctly with well balanced loads the protocol of examining a caliber against another is a fools errand.
Your post appears to be aimed at me and what I wrote in not only this thread, but in my 2005 Special Weapons article and on the old forum. I had originally intended to let it pass without comment, but since you seem to echo the posts of a couple other members that my proposed tests are unfair, biased and poorly designed, I feel compelled to respond.

Randomly picking a loading simply because it is an FMJ without any thought as to load development and bullet construction will at best misrepresent the capability of that caliber. The Wolf 110 will not be optimized for a military type range of targets but rather will be considered in the light of economical development and production. Equally the 120 Norma is in basis a hunting projectile for pelt and bird in Europe not a military construction.
The 110gr Wolf and 120gr Norma were not picked at random. They were selected by default, being the only suitable FMJs now (or soon to be) available.

As far as I can tell, the 120gr Norma is contructed like some Swedish military 6.5x55 projectiles; it just weighs less, being a bit shorter.

In the AA gel test photo posted a few years ago, the Norma FMJ produced a wound profile very similar to that of non-fragmenting 7.62 M80 Ball. I see no reason to think it would "misrepresent" the ability of 6.5 to penetrate concrete block, relative to lead-core 7.62 FMJ.

As for the 110gr Wolf, it may or may not do well at punching through cinder block, but something like it would be required for nations like the UK, for compliance with Hague Declaration III. It may have been designed for low-cost plinking, but that does not automatically exclude it from delivering military performance.

Just as it was not possible to quickly and cheaply rig high capacity magazines with string and gum, it was expounded that the Grendel could never offer such capability...
Who said that high-capacity magazines for 6.5 Grendel were impossible? Certainly I never did. What I wrote back in 2005 is that a 17-rd mag was the largest capacity then available.

...so we have argued that the same gum and gaffer tape approach must preclude its ability to operate from a belt. The case was made that it could not be pounded into an existing link on an existing feed tray. This morphs in the internet from a simple consideration into what looks like and exhaustive engineering study and when cursory reviewed by interested parties such information works heavily against us.
Yeah, that was unfortunate, but I can't keep some morons from misusing the information I provide, any more than AA can prevent people from misusing the guns you sell.

In this same approach what would be the interest in running commercial bullets in handloads against well established military calibers.
Because that is the only option currently available to get an apples-to-apples comparison of 6.5 lead-core FMJ vs 7.62 lead-core FMJ. I always prefer to use factory ammo in tests, but the Wolf FMJ load won't be here for some time yet.

The only alternative I can think of is that covered in my reply to noone: factory loads with TSX bullets, which is rather expensive.

We are at present undertaking to build T3 technology into the Grendel, a 6.5mm M855A1 if you will. Balance this loading into a SAFE cartridge which will offer weapon durability and you now have the basis of a simple study. Our apples to apples of military constructions is met and we have but to throw these from similar barrel lengths to start the examination.
That's truly great, but I was seeking information now, and had absolutely no idea when 6.5 T3 ammo might become available.

stanc

06-19-2011, 11:20 PM

The "right messengers" are possibly more critical than excellent tests. These are folks who, when convinced of the value of a new idea, can influence folks who control money in industry and government. They can take our test results and coarse analyses to the right folks and give the system a chance.
More than that, you need to convince Army leadership, especially the Chief of Staff. A determined CSA can push through a project, even if not needed. Stryker infantry vehicle is a prime example. GEN Shinseki really wanted it, and said it was needed because the Army did not then have an air-deployable, light-armored, infantry carrier. That was a blatant lie, because the M113 was (and still is) in the inventory, and holds the same number of infantrymen...and can be carried on C-5 and C17 transports in greater numbers than can Stryker. Despite that, Shinseki got Stryker rammed through the acquisition process, and fielded.

The moral to the story: If you want something adopted, get the CSA in love with it.

"Nothing is ever as good as what we've got if they decide not to spend the money. Of course if they really want something then what we're going after surpasses whatever we've got, regardless of test results."

noone

06-20-2011, 04:47 PM

It is my belief that the metalstorm "firearm" system, is a considerable leap forward in firearms technology. An earlier posting contended that there hasn't been a significant change in rifle design since the 1950's. To be sure, the metalstorm technology isn't currently mounted in a shoulder fired weapon, only a handgun design has been put forward. But I see the possibilities of the metalstorm system as a considerable leap forward in firearms technology.

The metalstorm system has been mounted up as everything from what looks like a square block of barrels filled with powder and projectiles, to a system that shoots 40mm grenades. It makes quite an area denial system.

JASmith

06-20-2011, 05:03 PM

The problem with Metalstorm is the same as with the extinct pepperpot rifles and pistols. Reloading appears to be cumbersome.

There are places where the technology is eminently sensible. Any remotely operated system, whether vehicle mounted or in a fixed position, would be well-served by the potentially inexpensive MetalStorm.

LR1955

06-20-2011, 07:39 PM

More than that, you need to convince Army leadership, especially the Chief of Staff. A determined CSA can push through a project, even if not needed. Stryker infantry vehicle is a prime example. GEN Shinseki really wanted it, and said it was needed because the Army did not then have an air-deployable, light-armored, infantry carrier. That was a blatant lie, because the M113 was (and still is) in the inventory, and holds the same number of infantrymen...and can be carried on C-5 and C17 transports in greater numbers than can Stryker. Despite that, Shinseki got Stryker rammed through the acquisition process, and fielded.

The moral to the story: If you want something adopted, get the CSA in love with it.

"Nothing is ever as good as what we've got if they decide not to spend the money. Of course if they really want something then what we're going after surpasses whatever we've got, regardless of test results."

Stan:

Although your views on the Stryker and how it got into the system are false, the notion that powerful people in the RTDE process can push forward a project is very sound.

LR1955

stanc

06-20-2011, 08:05 PM

Stan: ...your views on the Stryker and how it got into the system are false...
Gene:

What is false about what I wrote? Back around 2000-2004, there were a number of generals quoted in articles, and they said that air transportability was the primary reason for acquiring Stryker.

I didn't keep any of those articles, so am unable to cite, but here is an April 2002 quote from Shinseki:

"We realized it took us a long time to get heavy forces into the field. We knew we had to fix that. If this force had been ready Sept. 11, it would be in Afghanistan today."

The only way for the US Army to have put a light armor force into Afghanistan in 2001 was by air.

Stan

stanc

06-20-2011, 09:17 PM

LR1955

06-20-2011, 11:44 PM

P.S. If you don't believe Shinseki's own words, check out the Jan 2000 ORD.

www.fas.org/man/dod-101/sys/land/docs/bct/MAV-ORD-31-Jan-00.htm

Note the very first sentence: "An immediate and urgent need exists for an air transportable Interim Brigade Combat Team (IBCT), capable of deployment to anywhere on the globe in a combat ready configuration."

Are you still going to insist that I'm wrong?

Stan:

I insist that you have always hated the Stryker vehicle and nothing in the world is going to change your mind. You hated it when the concept was brought forth and hate it now.

The Stryker of 2K11 is far different than the ones of 2K2 and the concept has proven itself to be far superior to a 113 for the doctrine of the SBCT's.

So, why in the world do you want to bring it up again? I mean, the thread concerns testing and not the dead debate over what vehicle should be issued to SBCT's.

LR1955

stanc

06-21-2011, 12:52 AM

Stan: I insist that you have always hated the Stryker vehicle and nothing in the world is going to change your mind. You hated it when the concept was brought forth and hate it now.
Gene, you're wrong on that, too. I have never hated the Stryker. I like all armored vehicles, even those with wheels. What I disliked about the Stryker program is that it was spending hundreds of millions of $$$ to acquire a vehicle that -- because of its heavy weight and large size -- simply could not meet the stated purpose of the IBCT: an air-transportable armored unit that could get to anyplace on the globe in 96 hours.

The Stryker of 2K11 is far different than the ones of 2K2...
Even if that's true, it's irrelevant to the air-transportability issue.

...and the concept has proven itself to be far superior to a 113 for the doctrine of the SBCT's.
I don't dispute that Stryker is better than the M113 for getting around quickly on relatively easy terrain. (Stryker gets stuck in mud easier than the M113, though, and I suspect would be very inferior at breaking bush in the jungle, a la Vietnam War.)

However, that Stryker is well-suited for the way the SBCT is actually used, is a different subject from what I've always addressed. But, for some unfathomable reason you always seem to think Stryker's operational use in theatre disproves what I've said about it's strategic mobility. It doesn't. As the ORD proves, strategic mobility was the primary reason used to justify Stryker's purchase.

So, why in the world do you want to bring it up again? I mean, the thread concerns testing and not the dead debate over what vehicle should be issued to SBCT's.
I cited Stryker solely as background history to lead into my point that getting the CSA to like a concept seems to be the best way to get something adopted and fielded. It was the first example to come to mind, no doubt because I was heavily involved in the fight against it. You revived the debate when you erroneously claimed that what I wrote was false.

Another example is GEN Le May, who after shooting an AR15 at a picnic, decided that was the rifle he wanted to replace USAF M1 carbines. After some twists and turns, the Air Force did re-equip with the AR15/M16. (Maybe Alexander should invite the current CSA to a 4th of July picnic to shoot a Grendel... ;) )

A reverse example is the Garand rifle in .276 Pedersen. The Ordnance people liked it, and a review board recommended it for adoption, but the top Army leader (then-CSA GEN MacArthur) vetoed it, insisting upon staying with .30 caliber.

Oh, heck -- I suppose now you're going to accuse me of trying to revive the dead debates over whether the M16 rifle or .276 Pedersen cartridge should have been adopted... :eek:

Tony Williams

06-21-2011, 03:21 AM

I've taken a look at the Metal Storm system, with its advantages, drawbacks and potential uses, here: http://www.quarry.nildram.co.uk/MetalStorm.htm

warped

06-21-2011, 08:54 PM

I concur, MS is best used as an area denial weapon or like a CIWS.

It could be used on aircraft in a close support role as a grenade launcher or a mine layer.

noone

06-23-2011, 04:15 PM

Where I see the metalstorm as very useful for a number of applications (CIWS or area denial), storage of used barrels for reloading could cause a significant logistical problem. I presume they are too expensive to just throw away, or dump overboard, so once used, these units would need to be stored, and returned for reloading. Sure, we police up brass, and machine gun links at the range for re-use, but I think the logistics of that are quite different than the metalstorm units.

For remotely operated, or robotic area denial systems, the metal storm grenade system, in combination with some of the robotic mortar/mine deploying units could be really useful.

warped

06-24-2011, 04:44 PM

I concur, it becomes a logistical exercise that may not be very pleasant.

stanc

06-26-2011, 12:08 AM

Tony Williams

06-26-2011, 02:25 AM

By 6.5 and 7.0mm, do you mean .264" and .284", or .257" and .277" bullet diameters? It appears to me that it's the latter, which would mean that what we refer to as 6.5mm (as in 6.5 Grendel) wasn't even part of the test.

This seems to be corroborated by Gary Roberts, who wrote: "...the ARDEC caliber study that conclusively proves the superiority of .277" projectiles compared to smaller calibers..."

I mean .257 and .277 bore diameters, .264 and .284 bullet diameters.

I suspect that Gary Roberts was just following the military convention of giving calibres as bore diameters.

stanc

06-26-2011, 02:41 AM

I suspect that Gary Roberts was just following the military convention of giving calibres as bore diameters.
Probably not. He's a long-time supporter of 6.8 SPC (.277" bullet).

warped

06-26-2011, 02:55 AM

That was putting it mildly Stan....

LR1955

06-26-2011, 12:34 PM

Probably not. He's a long-time supporter of 6.8 SPC (.277" bullet).

Stan:

I talked with Roberts at length numerous times over the phone and as I can recall, AA did not submit a Grendel or ammo for that series of tests. And yes, at that time -- three or four years ago I believe -- the 6.8 performed better in jel than the issued ammo. That should not have been a surprise as the 6.8 that was tested was designed for CQB and you won't find many small arms cartridges differing to any significant degree in ballistics to 300 meters.

I recall the heated debates with him on the last forum with the continual implications that he skewed the testing and results in favor of the 6.8. I do not think he even played a role in the test protocols or the final report.

LR55

stanc

06-26-2011, 03:54 PM

I talked with Roberts at length numerous times over the phone and as I can recall, AA did not submit a Grendel or ammo for that series of tests. And yes, at that time -- three or four years ago I believe -- the 6.8 performed better in jel than the issued ammo.
Gene:

That's a different series of tests, which were done by an organization other than ARDEC. The ARDEC study currently being discussed was, as I understand, done within the last year or so, and apparently did not test cartridges like 6.8 SPC and 6.5 Grendel. According to what Tony posted previously, it was a comparison of different caliber bullets only.

If Tony's list is complete, then .224, .243, .264, .284 and .308 bullets were tested, with .257 and .277 omitted.

So the next question is, is Tony wrong about what bullets were evaluated, or is Gary mistaken about .277 being tested, let alone being the best performer?

Stan

Tony Williams

06-27-2011, 12:08 AM

Gene:

That's a different series of tests, which were done by an organization other than ARDEC. The ARDEC study currently being discussed was, as I understand, done within the last year or so, and apparently did not test cartridges like 6.8 SPC and 6.5 Grendel. According to what Tony posted previously, it was a comparison of different caliber bullets only.

If Tony's list is complete, then .224, .243, .264, .284 and .308 bullets were tested, with .257 and .277 omitted.

So the next question is, is Tony wrong about what bullets were evaluated, or is Gary mistaken about .277 being tested, let alone being the best performer?

Stan

The notes I have are a bit ambiguous, so I'm doing some checking over the exact calibres used.

They certainly fired the bullets from something, and measured the results out to 300m, but exactly which cartridge cases were used I'm not sure.

warped

06-27-2011, 03:31 AM

As I understood it, the .277 was omitted.

Bill Alexander

06-27-2011, 10:16 PM

Time will probably sort everything out.

As I understand the ARDEC study and read its contents then some of the things being touted are not exactly as others would wish them to be. This said this is a closed study with a restriction on the disemination of data. It is a pitiful situation when those who are so placed to be (officially)appraised of the work cannot keep their mouths shut.

In the community as a whole such behaviour now created chasms in how data is procured and leaves both contractors and staff suspitious as to the motives of otherwise useful entities.

stanc

06-27-2011, 10:26 PM

Okay, Gary Roberts posted the following on arfcom:

"As presented at a joint USG meeting this past March, the bullet diameters tested were described as: .224", .243", .257", .277", .308""

Converted from inch to metric measurement, those figures correspond to projectile diameters (not calibers!) of 5.7, 6.2, 6.5, 7.0 and 7.8mm, the sizes Tony said were tested.

Which means that it was .264" which was omitted from the test. The Army did about the same thing once before. When developing variations using the 7.62x51 case to create the "homologous" rounds, there was a .25-caliber version and a .27-caliber version, but no .26-caliber.

LRRPF52

06-27-2011, 11:55 PM

If the government is involved, I just think DMV + D.C., with at least 25% of the funds for whatever it was unaccounted for on average, so I don't look for much validity in anything coming from that hybernaculum.

We'd be better off giving the money they're most likely wasting back to the States so units can put it to their ammo training budgets. I just learned that the Pentagon controls 95% of my State's National Guard budget. Nice...I guess that's why they're not called State Guards anymore...

This ARDEC testing wouldn't surprise me if it was just one big spendex, with no real results coming from it...like OICW from the 50's. We have bigger problems to fix than caliber, that's for sure.

LRRPF52

warped

06-28-2011, 12:01 AM

That was the sound of money being flushed down the toilet.

In the end I think that was exactly the exercise, not doing anything but spending money was the important part.

Tony Williams

06-28-2011, 07:07 AM

warped

06-28-2011, 01:23 PM

If ever a new cartridge gets accepted for a NEW weapon, not just one for the existing platforms, I would bet even money it will look an awful lot like the 6.5x47Lapua.

If they only wanted to fit the AR/M series magazines it would be the Grendel

JASmith

06-28-2011, 01:49 PM

If ever a new cartridge gets accepted for a NEW weapon, not just one for the existing platforms, I would bet even money it will look an awful lot like the 6.5x47Lapua...
Do you mean the .260 Remington, the 6.5 Creedmoor, or an even shorter version of the .260 Rem?

warped

06-28-2011, 01:57 PM

JASmith

06-28-2011, 02:14 PM

That is a very good-looking cartridge!

From the functional point of view, you are very close to being on the mark.

On the political side: Referring to the recent discussions of the ARDEC test series and the inferred mental state of the folks who designed the test, it would look a little different and might be a caliber above or below.

warped

06-28-2011, 02:19 PM

I would wager as well that this cartridges genesis came from looking at the Grendel

When I was looking at the loaded cartridge it appeared to be a larger cased Grendel

JASmith

06-28-2011, 02:32 PM

"Great minds think alike!"

Tony Williams

06-28-2011, 03:40 PM

The problem with these 6.5mm rounds which are basically necked-down 7.62x51 is that they save very little space or weight over 7.62mm, and generate too much recoil for good controllability in auto rifle fire. So IMO they don't really meet the criteria to replace either 5.56mm or 7.62mm.

JASmith

06-28-2011, 04:36 PM

Tony,

You're spoiling our fun!

Your criteria are part of why Warped is probably right about a military cartridge fitting the AR-15 magazine well will likely be the Grendel. I would go as far as modifying the statement to one based on the Grendel...

A necked-down 6.8 SPC might have some adherents, but the brass is too long for decent 6.5 nose shapes. Maybe 6mm but I'm not so sure about the space there either. Going all the way down to 5.56 is about the best that case might do for getting decent nose shapes and velocity.

Cheers!
Joe

stanc

06-28-2011, 08:32 PM

Tony,

Your criteria are part of why Warped is probably right about a military cartridge fitting the AR-15 magazine well will likely be the Grendel. I would go as far as modifying the statement to one based on the Grendel...

A necked-down 6.8 SPC might have some adherents...
Me! Me! :cool:

...but the brass is too long for decent 6.5 nose shapes.
As is, yes. However, if the neck is trimmed by ~1 mm, the resulting 6.5x42 would permit use of bullets with an ogive like that of the Norma 120gr FMJ.

Maybe 6mm but I'm not so sure about the space there either.
Oh, yeah. A 6x42 on the SPC case? Me likem mucho grande! ;)

bwaites

06-28-2011, 09:04 PM

Me! Me! :cool:

As is, yes. However, if the neck is trimmed by ~1 mm, the resulting 6.5x42 would permit use of bullets with an ogive like that of the Norma 120gr FMJ.

Oh, yeah. A 6x42 on the SPC case? Me likem mucho grande! ;)

Naw, useless. Couldn't get the velocities you want from a 120 bullet. The 6.8 barely manages with short bullets. No way with anything with a decent BC.

A 6MM 105 or similar might work, but 6mm is barely better than 5.56, and I can't imagine the .mils considering such a minimal change.

Actually, scratch that, it wouldn't work. You would lose too much powder room even with the 6mm light bullets, at least the ones with decent BC's. It's been tried, and its why Robert Whitley is using the Grendel case in his 6mm AR and 6mm AR Turbo.

LRRPF52

06-28-2011, 09:42 PM

http://www.midwayusa.com/viewproduct/?productnumber=462149&cm_mmc=Froogle-_-Ammunition%20-%20Centerfire%20Rifle%20-%20Match%20%26%20Target-_-PriceCompListing-_-462149

http://media.midwayusa.com/productimages/medium/462/462149.jpg

And I really like the .260 rem

But if it were a new weapon design the 6.5x47 Lapua uses the case capacity more efficiently.

Think of it as the Grendel on performance enhancing drugs

108grain Scenar # Muzzle Velocity: 2952 fps
# Muzzle Energy: 2090 ft. lbs.

139 Scenar # Muzzle Velocity: 2690 fps
# Muzzle Energy: 2231 ft. lbs.

These appear to be mild loadings

Notice there is not a case intrusion problem on these

IIRC it works from existing 7.62NATO mags, therefore it would work from a .260 Mag

I have a friend shooting one, he says the cases are abnormally tough and can take far higher pressures than what the factory ammo is loaded to.

He shoots it in his AI.

A few guys I know have 6.5x47 Lapua's in AI's and other custom actions. My partner for FinnSniper last year used one, and made continual 1st-round hits at 900m on E-type silhouettes pushing 140gr Berger VLD's at well over 2900 fps. It's an awesome sniper round, and would be great for the M110.

I think barrel life would be an issue in an assault rifle and definitely an issue in an LMG. The small rifle primer with a .473" diameter case head could prove problematic in extreme cold weather as well. If the metallurgy is there with some of the treatments gaining popularity, it would be interesting to see barrel life increase with it, but we're talking about pressures way in excess of the 7.62 NATO.

It is a great caliber, but I think a bit much in case size for an assault rifle. An assault rifle still needs to be able to fit the basic profile of a shoulder-fired weapon that has the firepower of an SMG. That case diameter will not allow feasible 30rd mags, and remember that trends in mag capacity are increasing well above 30rds, not decreasing. Examples are the new Russian coffin mag for the AK100 series and An-94, as well as the Surefire and Magpul high-capacity mags.

The Grendel and 7.62 short are where I would draw the line on case diameter for a practical assault rifle. The MP44 presented problems with causing a larger profile for the shooter while in the prone, as does the AKM and variants, while the AR15 does not, even with a 30rd mag, which also serves as a great monopod.

stanc

06-28-2011, 10:08 PM

Naw, useless. Couldn't get the velocities you want from a 120 bullet. The 6.8 barely manages with short bullets. No way with anything with a decent BC.
I didn't say to use the 120gr Norma, just that a bullet with its ogive shape would (barely) fit in a 42mm case. The bullet would have to be lighter than 120gr, and BC would certainly be less than the more streamlined bullets suited to 6.5 Grendel, but to replace 5.56 only it might be worth testing.

A 6MM 105 or similar might work, but 6mm is barely better than 5.56, and I can't imagine the .mils considering such a minimal change.
Probably they wouldn't. Then again, 6mm was one of the bullets in the recent ARDEC tests.

Actually, scratch that, it wouldn't work. You would lose too much powder room even with the 6mm light bullets, at least the ones with decent BC's.
I don't see why it wouldn't work. The 90gr E-Tip and 95gr SMK have decent BCs, and look like they'd cut powder capacity less than a 123gr Scenar in the 6.5 Grendel case.

Regardless, I still like the idea. It'd be sort of a magnum version of the 1970s 6mm SAW round. Imagine if the M14 and M60 had been chambered for 6x42 (or better yet, 6x43, without the 2.25" length restriction), there would never have been a need for the M16 and M249!

http://www.youtube.com/watch?v=N06ySsT2EKU
http://www.youtube.com/watch?v=48pFvx4hlbo

LRRPF52

06-30-2011, 02:36 AM

Regardless, I still like the idea. It'd be sort of a magnum version of the 1970s 6mm SAW round. Imagine if the M14 and M60 had been chambered for 6x42 (or better yet, 6x43, without the 2.25" length restriction), there would never have been a need for the M16 and M249!

Other than the fact that the M14 and M60 have some of the worst reliability issues and most maintenance-intensive schedules of all the small arms I have ever used. Both those systems are a PITA to operate reliably, maintain with armorer support, and keep spare parts on-hand for. In short, they suck big time.

Now the SAW cartridge I do like, at least the concept of it, but it does push the weapon size envelope for an assault rifle. The Chinese have basically adopted that cartridge with the 5.8x42 in their QBZ95, LMG, and DMR. I've heard they're not happy with its downrange performance at distance though, but who really knows...

stanc

06-30-2011, 04:35 AM

Now the SAW cartridge I do like, at least the concept of it, but it does push the weapon size envelope for an assault rifle.
Yes, a little. But, nowhere near as much as Murray's 7mm UIAC. Although from a technical standpoint the 7x46 offers a slight advantage over 7.62x51, I think he's going down the wrong track.

The Chinese have basically adopted that cartridge with the 5.8x42 in their QBZ95, LMG, and DMR. I've heard they're not happy with its downrange performance at distance though, but who really knows...
They made the mistake of not going quite big enough. 6mm is the minimum necessary for long range, 6.35mm might've been the best, considering the trade-offs for minimum cartridge size and weight, and acceptable ballistics.

JASmith

06-30-2011, 05:40 AM

...They made the mistake of not going quite big enough. 6mm is the minimum necessary for long range, 6.35mm might've been the best, considering the trade-offs for minimum cartridge size and weight, and acceptable ballistics.
You're probably closer to the mark than most.

At the risk of re-plowing some ground, my thinking is that the 7.62X51 NATO will almost certainly continue to be the "light caliber" for vehicle-mounted weapons. I think it may be possible to go with a unified caliber for dismounted units, but sense that the emerging plastic-cased ammunition Tony has observed will keep the 7.62 in the heavier dismounted units as well.

This opens the door a crack for the intermediate caliber by decreasing the high-end requirement. It would truly be interesting to see what one could get from a family of Grendel-based cartridges in 5.56, 6, 6.35, and 6.5 mm. We should also examine a similar family based on the 6.8 SPC.

LR1955 and others have argued that probability of hit out to 400-600 meters is of critical importance and that any new system needs to shine in at least one area.

Given the fundamental need to get a hit, it seems odd that we've spent a lot of time discussing on-target effects, ammunition weight, and recoil but almost none on trajectory and wind-drift. These areas are ones where higher-velocity and moderately well-shaped bullets might result in a significant improvement.

stanc

06-30-2011, 07:04 AM

...my thinking is that the 7.62X51 NATO will almost certainly continue to be the "light caliber" for vehicle-mounted weapons.
Concur. The only complaint about 7.62x51 that I know of is the weight, and for vehicle-mounted weapons that is not a significant issue.

I think it may be possible to go with a unified caliber for dismounted units...
Sure, it's possible. In WWII and the Korean War, the infantry rifle, automatic rifle, and machine gun used the same caliber. The drawback to a unified caliber is that it results in ammunition and weapon that are heavier and bigger than needed by the rifleman.

It would truly be interesting to see what one could get from a family of Grendel-based cartridges in 5.56, 6, 6.35, and 6.5 mm. We should also examine a similar family based on the 6.8 SPC.
If, as I think likely, 7.62x51 remains in use for the MMG/GPMG, then the need is only for a cartridge to replace 5.56x45. IMO, that argues for a cartridge of minimum weight and bulk. The diameter of the Grendel case is less desirable than that of the SPC case, which is less desirable than than that of the 6mm SAW case, which is less desirable than that of the 5.45x39 case. Of course, cartridge size and weight must be balanced against the need for sufficiently improved terminal and exterior ballistics.

LR1955 and others have argued that probability of hit out to 400-600 meters is of critical importance and that any new system needs to shine in at least one area.

Given the fundamental need to get a hit, it seems odd that we've spent a lot of time discussing on-target effects, ammunition weight, and recoil but almost none on trajectory and wind-drift. These areas are ones where higher-velocity and moderately well-shaped bullets might result in a significant improvement.
They might. The few ballistics tables I still have from 2-4 years ago show a clear advantage in trajectory and drift for 6.5 Grendel over 6.8 SPC and 5.56 NATO. However, the 6.8 velocities I used were for SAAMI loads, not the newer Spec II ammo.

The introduction of Wilson Combat's 110gr @ 2700 fps (6.8 SPC) load may put that cartridge in a different light. SSA's 85gr TSX @ 3000 fps might also be interesting. I have a feeling that 6.5 Grendel trajectory and wind drift may not be significantly different than these 6.8 SPC loads out to 400-600 meters.

Tony Williams

06-30-2011, 07:30 AM

I agree that even if we get a new long-range intermediate round, heavy 7.62mm MGs will remain in service in a support role for a while, and in vehicle mountings for much longer.

However, I don't agree that the task is to replace the 5.56mm rather than the 7.62mm. My perception of the UK view is that the weight of 7.62mm belted MG ammo is a bigger issue for dismounted troops than any lack of performance of the 5.56mm. So a round which can match the hit probability and target effectiveness of the 7.62mm at 1,000m while saving a lot of weight will look very attractive. By definition, this will be a smaller-calibre round with a lighter recoil, so could also do a good job in replacing 5.56mm, thereby bringing other benefits with it.

IMO, 6.5mm Grendel is currently the closest to the ideal performance of any current cartridge. When using 123 grain Lapua it is significantly better than 7.62mm M80 in both wind drift and trajectory at 1,000m - a service ball bullet wouldn't be as good, but should be in the same ballpark.

stanc

06-30-2011, 08:22 AM

I don't agree that the task is to replace the 5.56mm rather than the 7.62mm. My perception of the UK view is that the weight of 7.62mm belted MG ammo is a bigger issue for dismounted troops than any lack of performance of the 5.56mm.
Hmm. That's just the reverse of what I got from your "bite the bullet" article and presentations.

IMO, 6.5mm Grendel is currently the closest to the ideal performance of any current cartridge.
That's what I used to think, too. However, with the switch from SAAMI to the Spec II chamber, 6.8 SPC is looking much better than it did. Muzzle velocity with bullets of the same weight and type, 6.8 SPC outdoes 6.5 Grendel by 200-300 fps. Since a new carbine/rifle/LMG need not have the M16 mag well dimensions, neither does cartridge OAL have to be 2.25 inches of the 5.56 round. Let cartridge length be 2.40 inches, and 6.8 SPC can use very streamlined bullets. Combined with the higher velocity, and now 6.8 SPC might not only equal 6.5 Grendel at long range, it might even beat it.

When using 123 grain Lapua it is significantly better than 7.62mm M80 in both wind drift and trajectory at 1,000m - a service ball bullet wouldn't be as good, but should be in the same ballpark.
I'm skeptical of that. The only real data we have to go on is for the 120gr Norma FMJ, which has a 0.428 BC. That's far below the 0.54 BC of the 123gr Scenar. I just don't see the BC of a 120gr FMJ getting above 0.44-0.45, and 110gr is said to be the "sweet spot" for this cartridge -- what's the likely BC for an FMJ of that weight? With a BC in the 0.42-0.45 range, to match 7.62 M80 trajectory and drift, it'd be necessary to have MV in the neighborhood of 2700 fps, and that just ain't gonna happen.

Tony Williams

06-30-2011, 08:46 AM

Hmm. That's just the reverse of what I got from your "bite the bullet" article and presentations.

True, but the situation continues to evolve. The widespread distribution of 7.62mm rifles and MGs down to section level (helped by the fact that the British have just joined the US in selecting the 7.62mm Minimi) has to a large degree addressed the range and (to some extent) the effectiveness issues of 5.56mm, but has created a new problem - ammo weight!

That's what I used to think, too. However, with the switch from SAAMI to the Spec II chamber, 6.8 SPC is looking much better than it did. Muzzle velocity with bullets of the same weight and type, 6.8 SPC outdoes 6.5 Grendel by 200-300 fps. Since a new carbine/rifle/LMG need not have the M16 mag well dimensions, neither does cartridge OAL have to be 2.25 inches of the 5.56 round. Let cartridge length be 2.40 inches, and 6.8 SPC can use very streamlined bullets. Combined with the higher velocity, and now 6.8 SPC might not only equal 6.5 Grendel at long range, it might even beat it.

I wouldn't argue with that: my suggested ideal cartridge in calibres between 6.5mm and 7mm is based on the 6.8 Rem case, but slightly longer, and with space for a much longer bullet. In terms of conventional ammunition technology, I think this could represent the ideal dimensions and proportions.

If we were sticking to lead+steel cored bullets I would choose 6.5mm as the ideal calibre, but with copper+steel (or even just steel) bullets as seems mandatory nowadays, getting sufficient weight within a reasonable length becomes a problem for long, VLD bullets. So I am agnostic over the exact calibre, it all depends on how the sums work out; the answer could be 6.8mm or even 7mm.

I'm skeptical of that. The only real data we have to go on is for the 120gr Norma FMJ, which has a 0.428 BC. That's far below the 0.54 BC of the 123gr Scenar. I just don't see the BC of a 120gr FMJ getting above 0.44-0.45, and 110gr is said to be the "sweet spot" for this cartridge -- what's the likely BC for an FMJ of that weight? With a BC in the 0.42-0.45 range, to match 7.62 M80 trajectory and drift, it'd be necessary to have MV in the neighborhood of 2700 fps, and that just ain't gonna happen.

Could be. We may be able to get away with being close enough to M80 performance for the difference not to be significant, rather than exactly matching it. However, if the long-range performance falls noticeably short then the new round won't be able to replace 7.62mm and the argument for it will thereby be substantially weakened IMO. That PKM is far too widely distributed in actually or potentially unfriendly hands for the troops to be expected to face it with weapons of inferior range.

JASmith

06-30-2011, 02:18 PM

True, but the situation continues to evolve. The widespread distribution of 7.62mm rifles and MGs down to section level (helped by the fact that the British have just joined the US in selecting the 7.62mm Minimi) has to a large degree addressed the range and (to some extent) the effectiveness issues of 5.56mm, but has created a new problem - ammo weight!
The plastic case technology you called our attention will make a huge difference and, and one could forecast, reduce the pressure to replace the 7.62X51 machine gun in the heavy dismounted role.

...We may be able to get away with being close enough to M80 performance for the difference not to be significant, rather than exactly matching it. However, if the long-range performance falls noticeably short then the new round won't be able to replace 7.62mm and the argument for it will thereby be substantially weakened IMO...
We (especially me) keep forgetting that we live in a combined arms world. There was a recent (History, History International, or Discover Channel - I don't remember which) segment on the Barret rifle development, history and future plans. They appear to have implemented a variant of their M-107 that uses the 25 mm grenades developed, IIRC, for the now defunct OICM family of weapons.

True -- a 16-20 lb weapon and even heavier ammunition may be challenging to lug around, but the developments are there and will affect the 1 km game. These developments show possibilities. E. g., I remember seeing discussions on the web (~5 years ago) featuring an experimental UK guided 12 gauge round.

While a guided 12 gauge round, for the time being, would almost certainly be horrifically expensive, an unguided variant could be developed today and use existing under-barrel mounts for many of the weapons already in service. Further, the payload could be combined effects, shrapnel plus a shaped charge. The shaped charge would likely be able to pierce 20-30 mm of armor plate, making it capable of defeating the most effective forecast body armor. This, coupled with sights like the Barrett BORS, could give the squad-level sharpshooter some very interesting teeth.

Bottom line -- I see these other developments as factors we can't or should not ignore.

When we factor that sort of thing into the assessment and are willing to accept one ammunition type (e. g. 85-90 gr 6.5) for box magazines and another (e. g. 115 to 130 gr 6.5 mm) for belted, while still maintaining the potential for interchangeability in emergencies, then a "one caliber" dismounted infantry solution appears feasible.

Tony Williams

06-30-2011, 03:00 PM

The plastic case technology you called our attention will make a huge difference and, and one could forecast, reduce the pressure to replace the 7.62X51 machine gun in the heavy dismounted role.

That depends on how the plastic-cased technology is introduced. One thing is for sure - both the guns and ammo will require entirely different manufacturing techniques than are used at present, so there's no particular advantage in retaining an existing calibre: they could and should start with a clean sheet.

The second point is that there isn't and never will be any relaxation of the pressure to reduce the weight of portable equipment and consumables (like ammo) so if the Army can get long-range performance comparable with the 7.62mm but with lighter ammo, they're likely to go for as much saving as possible. Which takes us back to a 6.5 to 7mm round.

We (especially me) keep forgetting that we live in a combined arms world. There was a recent (History, History International, or Discover Channel - I don't remember which) segment on the Barret rifle development, history and future plans. They appear to have implemented a variant of their M-107 that uses the 25 mm grenades developed, IIRC, for the now defunct OICM family of weapons.

True -- a 16-20 lb weapon and even heavier ammunition may be challenging to lug around, but the developments are there and will affect the 1 km game. These developments show possibilities. E. g., I remember seeing discussions on the web (~5 years ago) featuring an experimental UK guided 12 gauge round.

I don't doubt that we will see developments in weapon systems (my favourite idea is here: http://www.quarry.nildram.co.uk/MetalStorm.htm ) but there will always need to be rifles for precision targeting with minimal risk of collateral damage, which takes us back to the performance we want from these and therefore to the ammo...

When we factor that sort of thing into the assessment and are willing to accept one ammunition type (e. g. 85-90 gr 6.5) for box magazines and another (e. g. 115 to 130 gr 6.5 mm) for belted, while still maintaining the potential for interchangeability in emergencies, then a "one caliber" dismounted infantry solution appears feasible.

That could work in theory, but it seems to have a dubious history in practice. Both Spain and Japan introduced low-recoil versions of the 7.62mm NATO for rifle use, but these didn't seem to last. The Chinese also introduced light (assault rifle, LMG) and heavy (sniper rifle, GPMG) versions of their 5.8x42, but have begun to move towards a compromise "universal" loading instead. Maybe the complication is felt not to be worth it.

JASmith

06-30-2011, 03:39 PM

Tony,

You've done very well at positing the next family of weapons and ammunition, but an immediate step to that family may be larger than can be swallowed just now. Try to think incrementally from where we are today and where we need to go.

That depends on how the plastic-cased technology is introduced. One thing is for sure - both the guns and ammo will require entirely different manufacturing techniques than are used at present, so there's no particular advantage in retaining an existing calibre: they could and should start with a clean sheet.
Our enthusiasm needs to be tempered by the knowledge that fear of the unknown will always make change an incremental process -- unless our noses really get rubbed in it. At that point it may be too late...

The second point is that there isn't and never will be any relaxation of the pressure to reduce the weight of portable equipment and consumables (like ammo) so if the Army can get long-range performance comparable with the 7.62mm but with lighter ammo, they're likely to go for as much saving as possible. Which takes us back to a 6.5 to 7mm round.
Which is why a plastic-cased 5.56 with attachable 12 ga grenade launcher (already with plastic cases) may end up being a preferred solution. This could happen in spite of the superiority of the 6-6.5 mm class of bullets and cartridges as a result of "incremental" and "minimum weight" arguments combined.

That (multiple ammunition types) could work in theory, but it seems to have a dubious history in practice. Both Spain and Japan introduced low-recoil versions of the 7.62mm NATO for rifle use, but these didn't seem to last. The Chinese also introduced light (assault rifle, LMG) and heavy (sniper rifle, GPMG) versions of their 5.8x42, but have begun to move towards a compromise "universal" loading instead. Maybe the complication is felt not to be worth it.
We already have multiple ammunition types big time in both 5.56 and 7.62. The only remaining step is to allow the bullet weight in belted ammunition to be different than for box magazines. Indeed, there is no reason for a 100 round box magazine to have the same bullet weight as the 30 round assault rifle magazine.

Cheers!
Joe

stanc

06-30-2011, 05:37 PM

...the situation continues to evolve. The widespread distribution of 7.62mm rifles and MGs down to section level (helped by the fact that the British have just joined the US in selecting the 7.62mm Minimi) has to a large degree addressed the range and (to some extent) the effectiveness issues of 5.56mm, but has created a new problem - ammo weight!
I see. Back to the future. Seems we've (partially) returned to the 1950s in that regard. Kinda funny, actually.

I wouldn't argue with that: my suggested ideal cartridge in calibres between 6.5mm and 7mm is based on the 6.8 Rem case, but slightly longer, and with space for a much longer bullet. In terms of conventional ammunition technology, I think this could represent the ideal dimensions and proportions.
It might. One advantage to the 43mm SPC case is that it can be loaded to OAL of 2.25" for conversion of 5.56x45 weapons, or to OAL of 2.40-2.50" for use in a new platform.

If we were sticking to lead+steel cored bullets I would choose 6.5mm as the ideal calibre, but with copper+steel (or even just steel) bullets as seems mandatory nowadays, getting sufficient weight within a reasonable length becomes a problem for long, VLD bullets.
I agree. Almost everybody is still looking at lead-core bullets, when they should be doing "green" projectiles. I've been guilty of this myself, even after pointing out a year or two ago that bullets for alternative calibers should be (in the USA, anyway) of the M855A1/M80A1 type.

Bill Alexander was apparently paying attention, though, as he's trying to get a T3 bullet made for 6.5 Grendel. I can't help wondering how heavy a 6.5 T3 can be, without becoming too long. My calculations (which may be faulty) say that scaling down the 130gr M80A1 would be a mere 82gr in 6.5mm, and 149gr M80A1-A, only 94gr. That would certainly boost muzzle velocity, but downrange velocity would suffer significantly.

Then there is the question of terminal effects with the necessarily long, eco-friendly projectiles. Will they be capable of early yaw in flesh? Photos of M855A1 into bare gel, which would shed some light on that question, have yet to surface.

We may be able to get away with being close enough to M80 performance for the difference not to be significant, rather than exactly matching it. However, if the long-range performance falls noticeably short then the new round won't be able to replace 7.62mm and the argument for it will thereby be substantially weakened IMO.
Concur.

stanc

06-30-2011, 06:14 PM

...a plastic-cased 5.56 with attachable 12 ga grenade launcher (already with plastic cases) may end up being a preferred solution. This could happen in spite of the superiority of the 6-6.5 mm class of bullets and cartridges as a result of "incremental" and "minimum weight" arguments combined.
Didn't Tony post a few weeks ago that the LSAT people had been directed to stop work on 5.56 CL/CT ammo?

As for the 12ga idea, have you ever tried to hit a man-size target at 200-400 yards with a conventional slug? It's difficult enough with a regular shotgun, but likely near impossible with that underbarrel thing they have now.

We already have multiple ammunition types big time in both 5.56 and 7.62. The only remaining step is to allow the bullet weight in belted ammunition to be different than for box magazines.
Joe, the military has always had multiple ammunition types, at least as far back as the .45-70 era. And they've always had a single load standardized for rifle and machine gun. Special purpose rounds have sometimes been employed (for instance, 5.56 Mk262 and Mk318) for rifles, and standard Ball ammo in machine guns, but that's an exception for mission specific requirements.

The Army's SOP was and is one bullet weight for both mag-fed and belt-fed weapons, so any proposal for two different weight Ball projectiles is pretty much a non-starter, doomed to fail.

JASmith

06-30-2011, 06:52 PM

Didn't Tony post a few weeks ago that the LSAT people had been directed to stop work on 5.56 CL/CT ammo?

The plastic-cased 5.56 would not be an LSAT, but one compatible with existing weapons.

As for the 12ga idea, have you ever tried to hit a man-size target at 200-400 yards with a conventional slug? It's difficult enough with a regular shotgun, but likely near impossible with that underbarrel thing they have now.
Absolutely correct. Slugs from rifled shotgun barrels, however, can get closer to 1 moa.

Further, we're talking about a bursting round with an effects radius of at least 2-3 meters -- the effective target then becomes a tad larger than the standard silhouette.

The Army's SOP was and is one bullet weight for both mag-fed and belt-fed weapons, so any proposal for two different weight Ball projectiles is pretty much a non-starter, doomed to fail.
We currently have two different weights in 5.56 used in both rifles and machine guns. The 7.62 AP type is a heavier bullet than the M80 round.

The single bullet weight is generally driven by a desire to map trajectories into each other. That would not apply when differentiating by weapon type.

Regardless of what one calls it, bursting rounds reaching out to a km are almost certainly near-term implementable. That will change the requirement and drive the infantry round to a smaller caliber than 7mm and possibly mandate retention of the 5.56.

We need to see what cartridge would fare well in that environment. The same holds true for Tony's vision of replacing both with a single cartridge -- which seems to suggest a 6.5 - 7 mm cartridge somewhat longer than the 5.56.

Bottom line -- The more forcefully we argue for a particular solution at this point, the more we appear to have intuited the best choice and are building our analyses and testing to "prove" the correctness of our intuition. We are all more or less guilty of that tendency, so have to be especially careful to start with broad assumptions and see where the sticks fall.

stanc

06-30-2011, 07:24 PM

The plastic-cased 5.56 would not be an LSAT, but one compatible with existing weapons.
Been tried, many times. Hasn't worked.

We currently have two different weights in 5.56 used in both rifles and machine guns.
But not two different weight Ball rounds. Even the USMC, which is currently using two different type bullets for rifle and LMG (in Afghanistan), still uses the same (62gr) weight bullet in both weapons.

The 7.62 AP type is a heavier bullet than the M80 round.
Actually, the current 7.62 AP has a lighter bullet than the M80. And AP is not the standard load. It's a special purpose round, with limited use.

The single bullet weight is generally driven by a desire to map trajectories into each other.
I don't know what you mean by that. AFAIK, using a single bullet weight (and type) is primarily an application of the KISS principle.

The more forcefully we argue for a particular solution at this point, the more we appear to have intuited the best choice and are building our analyses and testing to "prove" the correctness of our intuition.
"What do you mean, 'we', white man," Tonto said to the Lone Ranger, as hostile Indians were closing in. ;)

JASmith

06-30-2011, 08:24 PM

Stan, Tony, et. al.,

We need to understand the arguments and technologies, e. g., plastic-cased 5.56 and bursting 12 gauge shells not from the likelihood they will be introduced, but from the point of view of arguments to against implementing something new.

Someone clinging to the notion that the 5.56 and the 7.62 are perfectly fine and "the best we can do" will gleefully grab these and even very speculative emerging technologies to "prove" that we need do nothing.

This makes the chore of advocating a new cartridge, or anything else new, enormously more difficult. So, whether one or more of us is convinced something will or won't happen, we need to carry options to deal with those alternatives.

For example, Tony argues that the imminent to near-term implementation of plastic-cased ammunition in 5.56 and 7.62 can be a trigger point opening the door for a unified cartridge. Not all of us draw the same conclusion. Nonetheless we spend a lot of time debating the configuration and merits of that cartridge.

Similar attention needs to be given to equally plausible alternative paths. To repeat my previous post, we need to consider the alternatives and dispense with them, even our favorite ones, on arguments more convincing that "that has been tried before." Technology changes with time, and that change opens the path to implementing long-standing ideas previously discarded because the then-new technology, threat, or fiscal environment couldn't support implementation.

stanc

06-30-2011, 10:54 PM

...whether one or more of us is convinced something will or won't happen, we need to carry options to deal with those alternatives.
Joe, it seems to me that you're overthinking this matter and making it immensely more complicated than it needs to be.

The goal is a simple one: Develop a cartridge that's significantly better than 5.56x45, without incurring excessive penalties in weight and magazine capacity.

For those who think a smaller, lighter round than 7.62x51 is needed for GPMG use, the goal is a cartridge with performance "good enough" to replace 7.62x51.

...attention needs to be given to equally plausible alternative paths. To repeat my previous post, we need to consider the alternatives and dispense with them, even our favorite ones, on arguments more convincing that "that has been tried before." Technology changes with time, and that change opens the path to implementing long-standing ideas previously discarded because the then-new technology, threat, or fiscal environment couldn't support implementation.
Give attention to plausible and feasible alternatives, certainly. But, I see no logic in being concerned with ideas that have been shown to be implausible or otherwise not worth pursuing. The task is difficult enough without devoting time and $$$ on ideas that have been demonstrated to not be viable.

stanc

07-01-2011, 01:30 AM

LR1955 and others have argued that probability of hit out to 400-600 meters is of critical importance and that any new system needs to shine in at least one area.

Given the fundamental need to get a hit, it seems odd that we've spent a lot of time discussing on-target effects, ammunition weight, and recoil but almost none on trajectory and wind-drift. These areas are ones where higher-velocity and moderately well-shaped bullets might result in a significant improvement.

If we were sticking to lead+steel cored bullets I would choose 6.5mm as the ideal calibre, but with copper+steel (or even just steel) bullets as seems mandatory nowadays, getting sufficient weight within a reasonable length becomes a problem for long, VLD bullets. So I am agnostic over the exact calibre, it all depends on how the sums work out; the answer could be 6.8mm or even 7mm.

We may be able to get away with being close enough to M80 performance for the difference not to be significant, rather than exactly matching it. However, if the long-range performance falls noticeably short then the new round won't be able to replace 7.62mm and the argument for it will thereby be substantially weakened IMO.
Curiosity got the better of me, so I ran some tables for comparison. Had to make some assumptions, estimations and extrapolations regarding muzzle velocities from 20-inch barrels, but I think the figures are fairly close. On the .277" and .264" bullets, I used the BCs for Barnes' solids as the best available surrogates for eco-friendly, military ball projectiles.

Range - yards _0_ _100 _200 _300 _400 _500 _600 _700 _800 _900 1000

.308" 147gr @ 2700fps BC=0.418
Velocity - fps 2700 2488 2285 2094 1912 1740 1579 1435 1306 1198 1111
Energy - ft-lb 2379 2019 1705 1430 1193 _988 _814 _672 _556 _468 _403
Path - inches 0.0 44.6 83.7 116.0 140.4 155.2 158.5 147.8 120.3 72.2 0.0
Drift - inches 0.0 _0.4 _1.6 __3.7 __6.9 _11.3 _17.0 _24.2 _33.1 43.6 55.9

.277" 120gr @ 2600fps BC=0.438
Velocity - fps 2600 2402 2213 2033 1862 1700 1550 1415 1294 1192 1110
Energy - ft-lb 1801 1537 1304 1101 _924 _770 _640 _533 _446 _379 _328
Path - inches 0.0 46.7 87.4 121.0 146.1 161.1 164.2 152.7 123.8 74.1 0.0
Drift - inches 0.0 _0.4 _1.6 __3.7 __6.9 _11.2 _16.9 _24.1 _32.8 43.1 55.0

.264" 110gr @ 2600fps BC=0.452
Velocity - fps 2600 2408 2224 2049 1883 1725 1577 1443 1322 1219 1134
Energy - ft-lb 1651 1416 1208 1025 _866 _726 _607 _509 _427 _363 _314
Path - inches 0.0 45.5 85.1 117.6 141.8 156.2 158.8 147.5 119.4 71.4 0.0
Drift - inches 0.0 _0.4 _1.5 __3.6 __6.7 _10.8 _16.3 _23.1 _31.4 41.4 52.8

Verry intrresting, no?

Arggh! The new forum format is too narrow for 1000-yard data. I guess future tables will have to be limited to 800 yards...

JASmith

07-01-2011, 02:30 AM

...Give attention to plausible and feasible alternatives, certainly. But, I see no logic in being concerned with ideas that have been shown to be implausible or otherwise not worth pursuing. The task is difficult enough without devoting time and $$$ on ideas that have been demonstrated to not be viable.
I've been there with other but still relevant military systems. The point is that the alternative cartridge will not be in competition with either 5.56 or the 7.62 or both. It will compete with other candidates whose adherents also believe their concepts are superior.

That's the major reason why I suggest a look at these alternatives. Our concept will need to both be significantly better in at least one aspect than the existing ammunition types and somehow be more attractive than these alternatives.

Some of the new-old ideas will prove to be viable and will affect the application space.

To repeat one more time -- the detractors will grab any specious argument.

JASmith

07-01-2011, 02:35 AM

Thanks for doing the legwork on the table!

I know you didn't, but it sure looks like the muzzle velocities and bullet weights were chosen to make trajectories for the three calibers look the same...

We don't seem to be getting traction on the long range game with these choices. That's the reason I have advocated looking at lighter, smaller bullets for the assault rifle and thinking about a half-kilometer instead of a full kilometer.

Tony Williams

07-01-2011, 09:29 AM

Tony Williams

07-01-2011, 09:39 AM

Then there is the question of terminal effects with the necessarily long, eco-friendly projectiles. Will they be capable of early yaw in flesh? Photos of M855A1 into bare gel, which would shed some light on that question, have yet to surface.

There's a theory doing the rounds of ammo development people in the UK that a long, pointed bullet will yaw more rapidly and reliably on impact than a short stubby one, because the if the bullet strikes with even a very small degree of yaw already (as most do), all of that mass much further back will make it a lot more unstable. I don't know if they've done any practical testing to demonstrate, that, though, and I'm rather dubious - I think that the construction and internal weight distribution has a greater effect than the shape. Just look at the difference between the yaw performance of the steel-cored 7.62x39 bullet compared with the Yugo lead-cored.

Tony Williams

07-01-2011, 09:44 AM

Curiosity got the better of me, so I ran some tables for comparison. Had to make some assumptions, estimations and extrapolations regarding muzzle velocities from 20-inch barrels, but I think the figures are fairly close. On the .277" and .264" bullets, I used the BCs for Barnes' solids as the best available surrogates for eco-friendly, military ball projectiles....

Thanks for doing that, very interesting. That seems to give us more leeway to play with different bullet weights than I had thought.

JASmith

07-01-2011, 02:03 PM

...I don't understand how plastic-cased 5.56 or 12ga mini-grenades have any relevance. :confused:
The relevance is that one absolutely needs to understand the competition.

Tony has discussed and provided enoiugh documentation for plastic cased ammunition enough that we really need to accept that these things will be perfected before LSAT. His argument is that this gives the community a chance to use their availability as a lever to introduce a new caliber. This would be an "interim" solution while LSAT, electric drives, lasers, etc. are brought to fruition.

12 gauge grenades can give an alternative infantry-friendly path for punch at ranges of about a kilometer. The point is that, while currently less credible than plastic-cased 7.62 or 5.56 cases, these guided grenades will be looked at as the mix changes. It has already been done for the OICW in 25 mm -- Barrett is hawking a M107 upper for the cartridge also.

These characteristics are attractive enough that folks will use them to either thwart new cartridge development in spite of immature development or as a bona-fide competitor to our ideas.

In either case, one will need to carry a documented discussion illustrating credibility of technology and showing where it fits in the vision or demonstrating that it is either inappropriate or the vision is superior.

stanc

07-01-2011, 05:16 PM

There's a theory doing the rounds of ammo development people in the UK that a long, pointed bullet will yaw more rapidly and reliably on impact than a short stubby one, because the if the bullet strikes with even a very small degree of yaw already (as most do), all of that mass much further back will make it a lot more unstable. I don't know if they've done any practical testing to demonstrate, that, though...
They probably haven't. And that theory doesn't seem supported by the wound profiles published by Martin Fackler and gel testing done by Gary Roberts and Bill Alexander.

...I think that the construction and internal weight distribution has a greater effect than the shape. Just look at the difference between the yaw performance of the steel-cored 7.62x39 bullet compared with the Yugo lead-cored.
Good examples, but I think it has nothing to do with steel core vs lead core construction. IMO, it's a result of external shape and internal weight distribution.

To look at your example above, the (steel core) M43 bullet is a long, boat tail design, with even weight distribution putting the CG near the midpoint of the projectile. The M67 bullet has the same length ogive, but being lead-core and flat base, it is short, which puts the CG more to the rear.

Another example is the 6.8mm 115gr FMJ vs 6.5mm 120gr FMJ. Both are lead-core construction (and nearly the same weight), but the 6.5mm bullet has greater L/D ratio and a more streamlined shape that -- like the 7.62mm M43 -- puts its CG close to the midpoint. In contrast, the 6.8mm FMJ is relatively short for its length, with CG more to the rear.

The long, streamlined 7.62mm M43 and 6.5mm FMJ bullets both show late yaw. The short, stubby 7.62mm M67 and 6.8mm FMJ projectiles both have early yaw.

The notable exception is the 5.45mm M74 bullet, which is long and streamlined, but yaws quickly after impact. IIRC, Fackler attributed this to imbalance resulting when the small lead plug in the nose shifts from the rapid deceleration upon impact. That type of construction probably can't be duplicated with "green" materials.

stanc

07-01-2011, 06:02 PM

The relevance is that one absolutely needs to understand the competition.

Tony has discussed and provided enoiugh documentation for plastic cased ammunition enough that we really need to accept that these things will be perfected before LSAT. His argument is that this gives the community a chance to use their availability as a lever to introduce a new caliber.

12 gauge grenades can give an alternative infantry-friendly path for punch at ranges of about a kilometer. The point is that, while currently less credible than plastic-cased 7.62 or 5.56 cases, these guided grenades will be looked at as the mix changes.
All of that may (or may not) be true, but I still don't see how it's relevant to the design and development of a new intermediate cartridge.

Does it affect choice of caliber, bullet type, muzzle velocity, or any other aspect of design?

JASmith

07-01-2011, 06:42 PM

...but I still don't see how it's relevant to the design and development of a new intermediate cartridge...
It becomes critically important if you want to take the design beyond the dilettante's wildcat cartridge and get a life in either the military or commercial worlds.

The design will have to reflect the marketing realities of one or both of those worlds.

stanc

07-01-2011, 06:52 PM

It becomes critically important if you want to take the design beyond the dilettante's wildcat cartridge and get a life in either the military or commercial worlds.

The design will have to reflect the marketing realities of one or both of those worlds.
That may be, but it avoids the question. In what way(s) does it affect choice of caliber, bullet type, muzzle velocity, or any other aspect of the cartridge design?

JASmith

07-01-2011, 07:43 PM

...In what way(s) does it (the competition) affect choice of caliber, bullet type, muzzle velocity, or any other aspect of the cartridge design?
Stan,

We've talked about this from as many different angles as I can think of.

Look at it this way -- the market sets thresholds. If your product doesn't meet those thresholds, it won't sell -- whether as a military or commercial item.

Others have pointed out that having something that is merely "better than 5.56 and 7.62" won't meet either the posited comparatively easy threshold implied nor the more challenging market realities. LR1955 has pointed out that we need "a 50%" improvement to get attention. We haven't yet identified anything that is even a 5% improvement in trajectory or on-target effects. Numbers are a different story, but that argument strongly favors the 5.56NATO. Hence the designs we've thought about likely won't make the cut.

Find a design combination that meets Gene's 50% plus-up in at least one aspect while maintaining rough parity in other performance factors and numbers, then you have a chance -- unless someone else identifies a 75% plus-up solution.

Combined arms considerations make the issue more complicated, but they need to be included in the discussion both to identify things that would compete and to find opportunities for properly defining the cartridge.

Thus the market affects "choice of caliber, bullet type, muzzle velocity, or any other aspect of the cartridge design" by ruling out certain combinations and favoring others.

stanc

07-01-2011, 08:27 PM

LR1955 has pointed out that we need "a 50%" improvement to get attention. We haven't yet identified anything that is even a 5% improvement...

Find a design combination that meets Gene's 50% plus-up in at least one aspect while maintaining rough parity in other performance factors and numbers, then you have a chance...
First, that's only Gene's opinion.

Second, history says he's wrong.

From .50-70 to 45-70 to .30-40 to 30-03 to 30-06 to 7.62x51, the Army made only "5%" improvements. (5.56x45 was forced upon them by the SecDef, so it's an anomaly in the historical trend.)

JASmith

07-01-2011, 10:33 PM

...From .50-70 to 45-70 to .30-40 to 30-03 to 30-06 to 7.62x51, the Army made only "5%" improvements. (5.56x45 was forced upon them by the SecDef, so it's an anomaly in the historical trend.)
I'm sure that Gene's 50% is more rhetorical than not. The facts are, however, that we will gain exactly zero traction if we are able to demonstrate only a 5% improvement absent a political decision to go to a new cartridge.

Also, the move from each of the cartridges to the next in the list had more than 5% improvements in one or more metrics. For example, the .45-70 had a slight improvement in velocity for a significantly smaller case. The .30-40 Krag had, IIRC a 220 grain bullet replacing the 400 grain+ 45-70 bullet and a lot more cartridges, and so on.

So yes, the improvement in some metrics in each of these may have been flat or a slight improvement, there were almost always significant improvements in one or more metrics. The exception may have been the 7.62X51 -- I don't know for sure but aside from the political issues (always trumping technical), the improvement was in weight of brass and a mild reduction in recoil at the expense of a slight reduction in velocity. The political issue was imposing a common cartridge on NATO and getting everyone to go with our beloved 30-06 would not have worked.

SecDef imposed the 5.56 DoD-wide because his metrics told him there was much more than 50% — doubling (100% improvement) the numbers of rounds per pound. This overrode issues like terminal effects simply because the 5.56 was viewed as adequate for the muzzle out to the 200 or so meter fight. For that matter, it still is.

stanc

07-01-2011, 11:04 PM

I'm sure that Gene's 50% is more rhetorical than not. The facts are, however, that we will gain exactly zero traction if we are able to demonstrate only a 5% improvement absent a political decision to go to a new cartridge.

Also, the move from each of the cartridges to the next in the list had more than 5% improvements in one or more metrics. For example, the .45-70 had a slight improvement in velocity for a significantly smaller case. The .30-40 Krag had, IIRC a 220 grain bullet replacing the 400 grain+ 45-70 bullet and a lot more cartridges, and so on.

So yes, the improvement in some metrics in each of these may have been flat or a slight improvement, there were almost always significant improvements in one or more metrics. The exception may have been the 7.62X51 -- the improvement was in weight of brass and a mild reduction in recoil at the expense of a slight reduction in velocity. The political issue was imposing a common cartridge on NATO and getting everyone to go with our beloved 30-06 would not have worked.
The US never wanted NATO to adopt .30-06. We wanted .30-06 performance and bullet size. The desired solution was 7.62x51, partly for the savings in brass (as you noted), and partly because it enabled a lighter rifle than was possible with .30-06.

SecDef imposed the 5.56 DoD-wide because his metrics told him there was much more than 50% — doubling (100% improvement) the numbers of rounds per pound.
Doubling the number of rounds was a definite advantage for 5.56x45, but I don't remember ever reading anything about that being the reason for the SecDef's decision. What I recall is that it was due to ongoing difficulties in M14 manufacture; the directive to buy M16 was meant to supplement the shortage of M14s as an interim measure until the SPIW -- expected to enter service in the late 1960s -- could replace both M14 and M16.

But, the reason for the SecDef's directive is immaterial to what I wrote. The 5.56x45 was forced upon the Army, therefore it cannot be taken into consideration as part of the historical trend in Army cartridge development. Left to itself, the Army would have stayed with 7.62x51 for infantry rifles, until the leadership decided to make another incremental change. My guess is that after prolonged combat experience (against the 7.62x39) in Vietnam, the next incremental step might've been something similar to the .30 HRT.
http://media.ar15.com/media/viewFile.html?i=19993

LR1955

07-01-2011, 11:21 PM

First, that's only Gene's opinion.

Second, history says he's wrong.

From .50-70 to 45-70 to .30-40 to 30-03 to 30-06 to 7.62x51, the Army made only "5%" improvements. (5.56x45 was forced upon them by the SecDef, so it's an anomaly in the historical trend.)

Stan:

History isn't always right either.

I am not sure it is a good argument to propose that just because history indicates we screwed up so many times, that we should just continue to follow historical trends.

What ever comes from all of this, if the result can't prove to be significantly better in one or more 'metrics' as Joe said, it stands no chance of being funded.

Since the military is about to take a huge hit in terms of budget, fat chance something new will be pushed unless it is not only a quantum improvement in performance but also much cheaper to produce.

LR55

stanc

07-01-2011, 11:45 PM

I am not sure it is a good argument to propose that just because history indicates we screwed up so many times, that we should just continue to follow historical trends.
Gene,

I don't know if all of those changes could rightly be judged as "screw-ups," or not. What I'm saying is that, when it comes to what they'll probably find acceptable in the present (and future), look at what their SOP has been in the past.

The only exception to this rule that comes to mind is the Stryker. Prior to Shinseki's reign as Chief of Staff, the Army's leadership was absolutely and fundamentally opposed to wheeled armored infantry vehicles. In spite of that institutional opposition, he managed to get it adopted.

Now, it could be you're right that any new small arms cartridge would have to deliver a "quantum" improvement. Since I can't read their minds to know if that's what they want, it seems logical to me to go by what they've habitually done before.

LR1955

07-03-2011, 12:40 AM

Gene,

I don't know if all of those changes could rightly be judged as "screw-ups," or not. What I'm saying is that, when it comes to what they'll probably find acceptable in the present (and future), look at what their SOP has been in the past.

The only exception to this rule that comes to mind is the Stryker. Prior to Shinseki's reign as Chief of Staff, the Army's leadership was absolutely and fundamentally opposed to wheeled armored infantry vehicles. In spite of that institutional opposition, he managed to get it adopted.

Now, it could be you're right that any new small arms cartridge would have to deliver a "quantum" improvement. Since I can't read their minds to know if that's what they want, it seems logical to me to go by what they've habitually done before.

Stan:

I never noted anyone in the RD arena willing to put money into something unless it represented a very significant improvement over what we have now. In addition it must meet some sort of requirement.

Although I do not know if any requirements exist for a new cartridge, my bets are that if one does exist it stipulates a statistical improvement in one or more areas over what exists now. And that such improvements are part of an overall system that includes the weapon and sighting system.

LR1955

stanc

07-03-2011, 01:15 AM

I never noted anyone in the RD arena willing to put money into something unless it represented a very significant improvement over what we have now.
I don't know how it can be determined in advance whether or not a project will produce "a very significant improvement over what we have now." It seems to me that can only be discovered via testing. (Hence the title of this thread. ;))

Although I do not know if any requirements exist for a new cartridge, my bets are that if one does exist it stipulates a statistical improvement in one or more areas over what exists now. And that such improvements are part of an overall system that includes the weapon and sighting system.
That may be. However, lacking such a requirements document, the most any of us can do is develop what we think is the best alternative cartridge. Then, if the leadership sees it and wants to make it an official Army project, they can create an ORD to justify funding further development.

stanc

07-05-2011, 03:50 AM

Tony Williams

07-05-2011, 06:55 AM

I presume they shoot standard NATO ball ammo in the L129A1 rifle? Do you know what muzzle velocity is from that 16" barrel? Maybe 2600 fps?

Yes, they shoot standard L2A2 ball (equivalent to M80). I've not seen a muzzle velocity quoted.

The decision to order what is meant to be a long-range sharpshooter rifle with such a short barrel is bizarre. Rumour has it that this came down to the opinion of one officer (in the right/wrong place) who thought it might make it more useful in urban combat.

Despite this, the L129A1 is well liked by the troops. Some would like it (or something like it) to be the new standard infantry rifle. But then, compared with an SA80 in 5.56mm...

stanc

07-06-2011, 12:48 AM

Tony, You've done very well at positing the next family of weapons and ammunition, but an immediate step to that family may be larger than can be swallowed just now. Try to think incrementally from where we are today and where we need to go.

I am, which is why I keep plugging the idea of firming up on the required calibre and ballistics using conventional technology first (preferably fielding some weapons in the new calibre for thorough testing), then transferring the lessons learned to the next phase of LSAT development.

If LSAT fails, then we can look at introducing the new calibre in conventional form but probably using lighter case materials (part-polymer, stainless steel and light-alloy are all being worked on at the present time).
I think this is a very good approach. However, I see a couple of problems to "firming up on the required calibre and ballistics."

1. There is no consensus as to whether:

Only 5.56x45 should be replaced.
Only 7.62x51 should be replaced.
Both 5.56x45 and 7.62x51 should be replaced.

Replacing only 5.56x45 with a bigger, heavier cartridge (like 6.5 Grendel and 6.8 SPC) increases the rifleman's carry load and/or decreases the number of rounds he carries, but does not change the machine gunner's load.

Relacing only 7.62x51 with a smaller, lighter cartridge (like 6.5x45 and 7x46) decreases the machine gunner's carry load and/or increases the number of rounds he carries, but it slightly increases the rifleman's load (if he is tasked to carry extra ammo for the machine gun).

Replacing both 5.56x45 and 7.62x51 with a single, intermediate cartridge (like 6.5x45 and 7x46) decreases the machine gunner's carry load and/or increases the number of rounds he carries, but it also substantially increases the rifleman's load (especially if he is tasked to carry extra ammo for the machine gun) and/or decreases the number of rounds he carries.

Then there is the (so far undiscussed) idea of replacing 5.56x45 with a bigger, heavier cartridge (but one not as big or heavy as 6.5 Grendel and 6.8 SPC), and replacing 7.62x51 with a smaller, lighter cartridge. This would impose less penalties on the rifleman than would a "unified" caliber.

2. There seems to be almost no publicly available test data on terminal effects of "eco-friendly" military ball projectiles. Without such data, how can we possibly make a logical, rational decision as to which caliber is optimum?

Tony Williams

07-06-2011, 01:34 AM

I think this is a very good approach. However, I see a couple of problems to "firming up on the required calibre and ballistics."

1. There is no consensus as to whether:

Only 5.56x45 should be replaced.
Only 7.62x51 should be replaced.
Both 5.56x45 and 7.62x51 should be replaced.

Replacing only 5.56x45 with a bigger, heavier cartridge (like 6.5 Grendel and 6.8 SPC) increases the rifleman's carry load and/or decreases the number of rounds he carries, but does not change the machine gunner's load.

Relacing only 7.62x51 with a smaller, lighter cartridge (like 6.5x45 and 7x46) decreases the machine gunner's carry load and/or increases the number of rounds he carries, but it slightly increases the rifleman's load (if he is tasked to carry extra ammo for the machine gun).

Replacing both 5.56x45 and 7.62x51 with a single, intermediate cartridge (like 6.5x45 and 7x46) decreases the machine gunner's carry load and/or increases the number of rounds he carries, but it also substantially increases the rifleman's load (especially if he is tasked to carry extra ammo for the machine gun) and/or decreases the number of rounds he carries.

Then there is the (so far undiscussed) idea of replacing 5.56x45 with a bigger, heavier cartridge (but one not as big or heavy as 6.5 Grendel and 6.8 SPC), and replacing 7.62x51 with a smaller, lighter cartridge. This would impose less penalties on the rifleman than would a "unified" caliber.

I don't see much prospect of a new round just to replace 5.56mm. The counter-argument will always be that 5.56mm is normally good enough (especially given M855A1 or MK318) and for circumstances in which it isn't good enough, there are 7.62mm weapons available.

Replacing the 7.62mm with a lighter round of equivalent long-range performance is likely to be more attractive to the army (US or UK) since they are very concerned about reducing the huge burden carried by dismounted troops. I may be wrong, but I get the distinct impression that with the return of 7.62mm rifles and LMGs to section level (which seem to have greatly impressed troops with their range and hitting power), 5.56mm is increasingly seen as a short-range carbine calibre which may not have much of a future in belt-fed LMGs. In which case, adopting a lighter replacement for the 7.62mm would reduce the load of infantrymen carrying ammo belts, not increase it.

By definition, a lighter, smaller-calibre long-range round to replace 7.62mm would also generate less recoil. Having tried HK 416 in 5.56mm and 6.8mm plus HK 417, all in quick succession, I found that the perceived (as opposed to calculated) recoil of the 6.8mm was much closer to the 5.56mm than to the 7.62mm. This makes a long-range intermediate round of similar power a realistic proposition for replacing 5.56mm in rifles and carbines. Yes, there would be some penalty in ammo weight (or alternatively the infantryman would carry fewer rounds) but the greater range and effectiveness of the ammo might well trump that. Especially given the work on advanced sighting systems which will make hitting targets at long range much easier. And, perhaps of the greatest appeal to the bean-counters, a unified calibre should save money - in halving the number of weapon types to be acquired, maintained and trained for.

2. There seems to be almost no publicly available test data on terminal effects of "eco-friendly" military ball projectiles. Without such data, how can we possibly make a logical, rational decision as to which caliber is optimum?

All I've seen are assurances that the M855A1 and the British 5.56mm HP produce more consistent terminal effects, but no evidence in support. But ARDEC did all the testing in different calibres using military-style green bullets and concluded that 6.8mm was best...

stanc

07-06-2011, 03:03 AM

I don't see much prospect of a new round just to replace 5.56mm. The counter-argument will always be that 5.56mm is normally good enough (especially given M855A1 or MK318) and for circumstances in which it isn't good enough, there are 7.62mm weapons available.

Replacing the 7.62mm with a lighter round of equivalent long-range performance is likely to be more attractive to the army (US or UK) since they are very concerned about reducing the huge burden carried by dismounted troops.

By definition, a lighter, smaller-calibre long-range round to replace 7.62mm would also generate less recoil. Having tried HK 416 in 5.56mm and 6.8mm plus HK 417, all in quick succession, I found that the perceived (as opposed to calculated) recoil of the 6.8mm was much closer to the 5.56mm than to the 7.62mm. This makes a long-range intermediate round of similar power a realistic proposition for replacing 5.56mm in rifles and carbines. Yes, there would be some penalty in ammo weight (or alternatively the infantryman would carry fewer rounds) but the greater range and effectiveness of the ammo might well trump that.
Those are very good points, with which I cannot find fault.

All I've seen are assurances that the M855A1 and the British 5.56mm HP produce more consistent terminal effects, but no evidence in support. But ARDEC did all the testing in different calibres using military-style green bullets and concluded that 6.8mm was best...
I'm willing to accept 6.8mm was indeed the best. But, since the only intermediate calibers reportedly tested were 6mm, 6.35mm, and 6.8mm, I'm not at all surprised that 6.8mm proved best.

There's no way to be certain how 6.5mm and 7mm would perform relative to 6.8mm in the same test conditions. However, as has been widely reported in the past, the SPC developers found 7mm gave better terminal effects than 6.8mm, and 6.5mm was worse.

Given "green" bullets of the same type construction, with the same sectional density and shape, and launched at the same velocity, it seems reasonable to think the bigger the caliber, the better the terminal effects, be it penetration of "hard" targets, or wound profile in ordnance gelatin. There's simply no substititute for mass. (Except in the silly, steel helmet penetration test. :rolleyes:)

Since the ballistics tables I ran a few days ago show a match to 7.62mm trajectory and wind drift with both 6.5mm 110gr and 6.8mm 120gr (and probably also with a hypothetical 7mm 130gr), I guess the next question is, what trade-off between cartridge weight and terminal effects is acceptable?

If minimum weight/recoil is desired, and minimum effectiveness is acceptable, go with 6.5mm. If maximum weight and recoil is okay in order to achieve maximum target effects, 7mm is the best choice. As with the SPC, 6.8mm would be in between 6.5mm and 7mm, both in weight, recoil, and terminal effects.

Unless priority is placed on really minimizing weight and recoil, 6.35mm and 6mm are probably not worth considering. The farther down we go from 7.62mm, the farther away we get from 7.62mm destructive ability.

Tony Williams

07-06-2011, 07:07 AM

Since the ballistics tables I ran a few days ago show a match to 7.62mm trajectory and wind drift with both 6.5mm 110gr and 6.8mm 120gr (and probably also with a hypothetical 7mm 130gr), I guess the next question is, what trade-off between cartridge weight and terminal effects is acceptable?

If minimum weight/recoil is desired, and minimum effectiveness is acceptable, go with 6.5mm. If maximum weight and recoil is okay in order to achieve maximum target effects, 7mm is the best choice. As with the SPC, 6.8mm would be in between 6.5mm and 7mm, both in weight, recoil, and terminal effects.

Unless priority is placed on really minimizing weight and recoil, 6.35mm and 6mm are probably not worth considering. The farther down we go from 7.62mm, the farther away we get from 7.62mm destructive ability.

I agree with all of that.

Tony Williams

07-06-2011, 09:12 AM

I don't have strong views - any would do, they just have slightly different strengths and weaknesses.

If we were considering lead-cored bullets then I would definitely go for 6.5mm. With non-lead bullets it may be that a larger calibre is needed to get a reasonable weight. On the other hand, we don't want the weight to be too close to the 7.62mm or it won't be worth changing. So maybe 6.8mm would be the right compromise, but probably with a slightly bigger case and certainly with space for longer, more aerodynamic bullets than the 6.8 Rem. In fact, the late 1940s .270 British looks pretty close: 6.8mm calibre, case length 46mm, case diameter 11.2mm (.441). Pretty much the same as Cris Murray's 7x46 UIAC necked-down slightly.

JASmith

07-06-2011, 02:23 PM

...Replacing the 7.62mm with a lighter round of equivalent long-range performance is likely to be more attractive to the army (US or UK) since they are very concerned about reducing the huge burden carried by dismounted troops.
...
Tony,

We've come a long way in our community discussions!

Shifting focus to the 7.62 makes a difference, with the Grendel representing the minimum caliber and case volume that should be considered.

I'm also suspicious of the claims of superiority in 6.8. I could see the point if one is looking only at ranges of 300 meters and under combined with a fiat that the maximum size base diameter is 0.425 and that the cartridge fit within an AR15. These are all legitimate constraints for the testing -- especially if the most mature senior officials approve.

The focus on 7.62 replacement relaxes both the length and the body diameter constraints a bit.

I don't remember off-hand if the explorations in Military Guns & Ammunition looked at a 0.445" diameter body and a COAL of 2.81" but a cartridge meeting these constraints might be the best shot at an attractive 7.62 replacement for dismounted infantry. This longer overall length eliminates most of the debate over whether "green" bullets will be implementable. They exist and do well in sporting rifles with the longer cases. We will also need to contend with the consequences of the almost certain retention of 7.62X51 for aircraft and vehicle-mounted applications.

My take on the community discussions coupled with my own assessments gives me the following thoughts:

I am very sure 6.5 will be the optimal choice both in the analytic and test world. A reasonable study, however, would consider .25 caliber, 6.5, 6.8, and 7mm.

I am very sure that gelatin-based tests will show little or no practical difference between optimized bullets in these calibers and be close enough to that of the 7.62 M80 to count.

The M855A1 propaganda suggests that properly designed bullets in these calibers are also likely make choosing between the calibers difficult

How much a caliber improves the soldier's ability to hit in this family of cartridges will likely be the deciding factor. This favors the smaller calibers because

Bullets of equal sectional density have slightly higher muzzle velocity in the smaller calibers for the same case volume
Bullets of equal sectional density can get slightly better ballistic coefficients in the smaller calibers.
Bullets of equal sectional density are lighter in the smaller calibers, reducing recoil.

Hope the summary is useful!

Cheers!
Joe

Tony Williams

07-06-2011, 02:44 PM

Shifting focus to the 7.62 makes a difference, with the Grendel representing the minimum caliber and case volume that should be considered.

I agree, on both counts. I would say that the old British 7x43 represents the top end (or its modern equivalent, Cris's 7x46 UIAC).

I am very sure 6.5 will be the optimal choice both in the analytic and test world. A reasonable study, however, would consider .25 caliber, 6.5, 6.8, and 7mm.

I am very sure that gelatin-based tests will show little or no practical difference between optimized bullets in these calibers and be close enough to that of the 7.62 M80 to count.

The M855A1 propaganda suggests that properly designed bullets in these calibers are also likely make choosing between the calibers difficult

How much a caliber improves the soldier's ability to hit in this family of cartridges will likely be the deciding factor. This favors the smaller calibers because

Bullets of equal sectional density have slightly higher muzzle velocity in the smaller calibers for the same case volume
Bullets of equal sectional density can get slightly better ballistic coefficients in the smaller calibers.
Bullets of equal sectional density are lighter in the smaller calibers, reducing recoil.

All true, but the need to plough through barriers and to maximise the wound channel for non-critical hits argue for the bigger calibres.

JASmith

07-06-2011, 03:46 PM

...All true, but the need to plough through barriers and to maximise the wound channel for non-critical hits argue for the bigger calibres.
I see convergence in the discussions.

Regarding the bigger calibres, there is no question that the bigger calibers with similar bullet shapes will perform better against barriers and generate bigger wound channels.

The difference is that we are striving to define a cartridge that can replace the 7.62X51 M80 round while reducing weight and recoil. In this model, we don't need the best performing round, just the one that slightly beats the M80 in all categories save for the one or two that really count.

So, while I can't yet claim to know the optimum caliber/cartridge combination, the stretched Grendel (similar to the Czech-based designs you've been looking at) seems like an excellent starting point.

Remember that the longer range engagements will tend to be dominated by weapons other than rifles. My view is that, in spite of my own fantasies of long-range marksmanship, the purpose of the rifle in to 600 to 1200 meter range is as much to keep the adversary honest while bigger weapons are brought to bear.

Fortunately, the 50+ year-old design of the M80 gives us a fair bit of wiggle room. This means that we have an opportunity to reduce weight and recoil while improving hit probability and numbers of rounds in the magazine and still be able to demonstrate at least M80 equivalence given a hit.

stanc

07-06-2011, 06:36 PM

The focus on 7.62 replacement relaxes both the length and the body diameter constraints a bit.

I don't remember off-hand if the explorations in Military Guns & Ammunition looked at a 0.445" diameter body and a COAL of 2.81" but a cartridge meeting these constraints might be the best shot at an attractive 7.62 replacement for dismounted infantry.
Disagree. To paraphrase Tony, if a cartridge is too close in bulk and weight to 7.62 NATO, then it won't be worth changing. Diameter of 0.44" and length of 2.8" is, IMO, much too close to the 0.47" / 2.8" of 7.62x51.

How much a caliber improves the soldier's ability to hit in this family of cartridges will likely be the deciding factor.
Disagree. All of the intermediate cartridges proposed to replace 7.62x51 can be expected -- if only because of reduced recoil -- to improve hit probability over that of the 7.62 NATO round.

IMO, the deciding factor is probably more psychological: how close to 7.62 terminal effectiveness does the alternative round deliver. If a new cartridge doesn't get close enough to 7.62 in "punching power," it won't have emotional appeal.

Remember, rounds like 6.5 Grendel and 6.8 SPC were aimed at replacing 5.56 NATO, to improve performance of the carbine and rifle. The concept being discussed now is intended to replace 7.62 NATO, to reduce the ammo weight of the GPMG and DMR.

JASmith

07-06-2011, 07:04 PM

...Diameter of 0.44" and length of 2.8" is, IMO, much too close to the 0.47" / 2.8" of 7.62x51...
This is Grendel-class diameter - same as 7.62X39 and the 6.5x45 Czech within a 2-3 thousandths of an inch. Going down to say, the .422" of the 6.8 SPC / .25 Remington reduces the powder capacity a bit much, even if the COAL is the 2.80" allowable within the 7.62X51 envelope.

We will need this powder capacity to get adequate muzzle velocity -- especially if it becomes clear that the 7mm is the minimum caliber.

Even so, we will be challenged to show that a 6-8 gram bullet of any caliber can be as effective as the 9.5 gram M80 round -- this in spite of reasonably sure knowledge that these are highly capable bullet weights in the calibers we're discussing.

JASmith

07-06-2011, 07:16 PM

...we do need the round with the best performance, all factors considered...
That's the catch -- optimization is all about trades within constraints.

We can't do significantly better than the 7.62 in every category. In fact, Tony and his correspondents have talked an awful lot about an 8 gram bullet at about 2750 ft/sec. This means that we are already trading away muzzle energy. There will be other areas where our quest for reduced weight will negatively impact one or performance parameters.

Our challenge will be to find the cartridge that does well-enough. Demanding that the cartridge be at least as good as the 7.62X51 in every category means that we rename the .308 Winchester, and merely use a better 9.5 gram bullet. We would then get the weight savings by counting on the adoption of the hoped-for plastic cases.

We've got to have and to identify legitimate trade space.

JASmith

07-06-2011, 07:56 PM

Muzzle velocities of 2600 ft/sec won't hack either the trajectory or the ho-ho test.

Your plots of a week or so ago focused solely on the 1 kilometer game. The .277 bullet in fact did not do as well even at that long range. These cartridges will need to do at least as well as the current M80 in the 0-300 meter and 300-500 meter games.

Any new cartridge will need to have at least 2750 ft/sec muzzle velocity to be competitive in the shorter game and to satisfy the TALAR (that looks about right) test that the senior decision makers are sure to apply.

JASmith

07-06-2011, 08:51 PM

I guess we're not on the same page...especially since "ho-ho" is the same as LOL and suggests my view that the senior folks would indeed laugh out loud if presented a "new" infantry cartridge producing a puny muzzle velocity.

Tony Williams

07-07-2011, 12:02 AM

Your plots of a week or so ago focused solely on the 1 kilometer game. The .277 bullet in fact did not do as well even at that long range. These cartridges will need to do at least as well as the current M80 in the 0-300 meter and 300-500 meter games.

I don't believe it is possible for a significantly lighter, lower-powered cartridge to match every aspect of the M80's performance at every range: that would defy the laws of physics.

What a general-purpose round needs to do is to match the M80 at long range, while being significantly more effective than 5.56mm at short range. This should be possible given a bullet that is both aerodynamic and designed to yaw reliably on impact.

After all, we are constantly being told by the military that 5.56mm is good enough at up to c.400 metres, and the only reason for carrying 7.62mm weapons is to reach out to longer ranges than this. Personally, I'm not convinced by that - too many soldiers I've listened to would rather have 7.62mm than 5.56mm at any range - but other things being equal a new intermediate should be significantly better than 5.56mm in barrier penetration and wounding effect at short ranges, an advantage which would growth with distance until it was comparable with M80.

JASmith

07-07-2011, 12:09 AM

Tony,

Concur...

Apologies -- I neglected to include the caveat that the statement applies to the trajectories. The M855A1 shoots a tad flatter than the M80 in the 100-300 game.

Tony Williams

07-07-2011, 12:22 AM

A brief comment on case capacities: I would rather have a bit more than is strictly necessary, for two reasons: this provides a margin for accommodating very long bullets (e.g. lead-free tracers) protruding back within the case without raising pressures; and it also allows for the possible use of a polymer case (with metal base) which will be thicker and will therefore reduce capacity.

JASmith

07-07-2011, 12:49 AM

...I don't know where your 2750 fps figure comes from...
I got the value from Gary's ammunition: http://www.inetres.com/gp/military/infantry/rifle/762mm_ammo.html

Note that the value is for 78 ft from the muzzle -- I couldn't find a call-out for barrel length.

The difference between 2700 and 2750 ft/sec is within the normal spread of chronograph testing. As with Tony's comment, we want to err a tiny bit on the high side in those performance parameters that we want to equal or best the M80.

Can't do it with everything, else we get some grotesque requirements. We also need to keep the parameters where we demand "significant" improvement to an absolute minimum for the same reason.

Tony Williams

07-07-2011, 01:01 AM

Of course, we can debate the meaning of "significant" :cool:

Statistically speaking, it simply means a result which could not have been achieved by chance. That is, if you compare a new intermediate with the M855 in terms of their average barrier penetration or gel test permanent channel size, the new intermediate should be clearly superior.

Barrier penetration can be quantified more precisely, but gel test channels are more difficult since it's not just the volume of the permanent channel which matters but the distance at which it reaches its maximum width.

stanc

07-07-2011, 01:42 AM

I got the value from Gary's ammunition: http://www.inetres.com/gp/military/infantry/rifle/762mm_ammo.html

Note that the value is for 78 ft from the muzzle
Yes, that info is the same as in TM43-0001-27.

I couldn't find a call-out for barrel length.
Nor does the TM give it. However, giving MV from 24" barrel is pretty much industry standard for high-power rounds, so I think it's logical to assume (despite the proverbial warning about assuming anything) that the data is for 24" barrel. And IIRC, for the last 100 years, the standard barrel length of .30-caliber infantry rifles and machine guns has been 24 inches (except for the M14, at 22 inches).

The difference between 2700 and 2750 ft/sec is within the normal spread of chronograph testing.
Chronographed velocities can vary widely, depending on the operator skill, ambient temperature, ammo manufacturer, and other factors. IMO, it's better to use the nominal velocity, as listed in the manual.

When this came up earlier, I ran ballistics tables to determine what muzzle velocity would give 2750 fps velocity @ 78 feet. The result was just a hair over 2800 fps (more specifically, 2805 fps).

As with Tony's comment, we want to err a tiny bit on the high side in those performance parameters that we want to equal or best the M80.
That's prudent, but it will make a cartridge bigger and heavier than absolutely necessary. Remember, the only advantage of this concept is the reduction of weight and bulk relative to 7.62x51. The bigger and heavier you make it, the less that advantage.

Can't do it with everything, else we get some grotesque requirements. We also need to keep the parameters where we demand "significant" improvement to an absolute minimum for the same reason.
IMO, the only areas that need to show "significant" improvement over 7.62 M80 are cartridge weight and bulk. Indeed, they are the only areas that can possibly be significantly better.

Muzzle velocity should equal M80, for reasons previously stated.

Terminal effects must be very similar, if not equal, to those of M80, again for reasons previously stated.

Downrange velocities, trajectory, and wind drift should be comparable, if not equal, to M80. The closer they match, the better, partly for psychological appeal, and partly to permit use of optical sights with 7.62 ballistic reticles.

JASmith

07-07-2011, 02:11 AM

Of course, we can debate the meaning of "significant" :cool:

Statistically speaking, it simply means a result which could not have been achieved by chance...
That's on the money!

Frankly, I was using a looser meaning of the definition -- one more in line with Gene's 50% plus up. We could start with numbers of rounds per kilogram and/or numbers of rounds in a magazine the size of the current 20 round magazine. Don't know if 50% is the right threshold.

Yes, it would need to be demonstrated to the standard you called our attention to.:cool:

stanc

07-07-2011, 03:31 AM

I was using a looser meaning of the definition -- one more in line with Gene's 50% plus up. We could start with numbers of rounds per kilogram and/or numbers of rounds in a magazine the size of the current 20 round magazine. Don't know if 50% is the right threshold.
There is no "right" threshold. Any figure you set will be arbitrary, neither right nor wrong.

Don't bother trying to set a threshold. Just design and develop the cartridge, then compare its weight to that of 7.62 M80.

It's a simple matter to compare the number of rounds in a mag the size of the current 20-round mag. A stack of 10 rounds of 7.62 will measure 4.73 inches. Divide by 0.441" and 0.422" case diameters, and you get the following:

7.62x51 -- 20 rds
7x46 ----- 21 rds
6.8x43 --- 22 rds

Not a very "significant" difference, is it? ;)

I'd say it's better to compare weight of 100 rds of linked ammo.

Individual links don't weigh much, but 100 of them do add up. Also, links for the .422" case can be smaller and lighter than those for a .441" case. The latter will likely be about midway in size and weight between the 6mm SAW link (which is a near perfect fit to the 6.8x43 case) and the 7.62 M13 link.

Another possible basis for comparison is the volume occupied by 100 rounds. Last I saw, 200 rounds of linked 7.62x51 is packed in a .30-caliber ammo can, 100 rounds in each of two heavy paper cartons (one carton per bandolier). If you can somehow determine how many 100-rd belts of the alternative cartridges can be packed in cartons, in a .30 caliber can, that may show an advantage. Just intuitively, I doubt that a .441" cartridge will permit more than two, 100-rd belts per can, but it might be possible (emphasis on "possible") that three, 100-rd belts of a .422" round could fit.

Yes, it would need to be demonstrated to the standard you called our attention to.:cool:
What standard is that? Did I miss it? :confused:

JASmith

07-07-2011, 04:23 AM

...It's a simple matter to compare the number of rounds in a mag the size of the current 20-round mag. A stack of 10 rounds of 7.62 will measure 4.73 inches. Divide by 0.441" and 0.422" case diameters...
It's a LOT more complicated than that. The current 7.62X51 magazine is not strictly a single stack as implied by your math. Changing the cartridge diameter changes the available number of cartridges in a non-linear fashion.

What standard is that? Did I miss it? :confused:
Check Tony's explanation of significance in today's post #140 at 6:01 PM.

JASmith

07-07-2011, 02:25 PM

You could be right -- but we'll need more than a cartoon to resolve. Problem is, I was (and might still be) under the impression that there's a gap between the cartridges.

'Sorry 'bout complications, but that's the way life is. Simplify where possible, but make sure nothing important gets left out in the simplification.

In the way of complications -- if the magazine is purpose-built for the cartridge and, as you point out, the cartridges are stacked as efficiently as possible (the reason for the double contact between bases), then the magazine thickness also decreases.

Read it earlier today. Didn't see any "standard" in it then, don't see one now.
(sigh...) Oh well, another indication of not being on the same page.

I hope we get it worked through!

stanc

07-07-2011, 06:48 PM

I'd say it's better to compare weight of 100 rds of linked ammo.

Individual links don't weigh much, but 100 of them do add up. Also, links for the .422" case can be smaller and lighter than those for a .441" case. The latter will likely be about midway in size and weight between the 6mm SAW link (which is a near perfect fit to the 6.8x43 case) and the 7.62 M13 link.
Some figures for your consideration.

7.62x51 (147gr bullet) -- Ctg: 392 gr / Link: 65gr
7x46 (130gr bullet) ----- Ctg: 292 gr / Link: 50gr
6.8x43 (110gr bullet) --- Ctg: 263 gr / Link: 35gr

100rds of linked 7.62x51 -- 6.53 lbs
100rds of linked 7x46 ----- 4.89 lbs
100rds of linked 6.8x43 --- 4.25 lbs

Obviously, 100 linked rounds of Tony's proposed 6.5-7x45 would have a weight somewhere in between 7x46 and 6.8x43.
http://www.ammunitionstore.com/product_images/c/142/308TracerLink__93954__64427_zoom.jpg

JASmith

07-07-2011, 09:02 PM

Just for grins, run the numbers for the 7.62X39....

JASmith

07-07-2011, 10:04 PM

Try 281 grains for the 7.62X39 (about halfway down the page at http://en.wikipedia.org/wiki/Comparison_of_the_AK-47_and_M16)

I would also interpolate the clips for the disintegrating belt so one could get a rough estimate of apples to apples comparison.

stanc

07-08-2011, 05:12 AM

If we were considering lead-cored bullets then I would definitely go for 6.5mm. With non-lead bullets it may be that a larger calibre is needed to get a reasonable weight.
I got to thinking (Which is always dangerous! ;)) about that. Did a rough sketch of a 6.5mm "EPR" projectile, modifying the 120gr GMX with an M855A1-type penetrator. (See attached.) I don't know how to make a close estimate of what the bullet weight would be reduced to by using steel where higher-density gilding metal was previously, but it would almost certainly weigh less than 120 grains, perhaps 115 or so?

Note that, compared to M855A1, the 6.5mm penetrator is much longer relative to bullet length, and the base slug is much shorter. Also, at 1.403" length, the base of the 6.5mm bullet will extend rather deep into the cartridge case, reducing the powder volume. The solution would seem to be shortening the tail end of the projectile, and thereby increase powder space.

However, shortening the bullet's rear will further reduce weight, to maybe 105 grains? That would also reduce the BC, possibly impacting trajectory and retained velocity/energy. But, it'd enable MV to increase, which is good. A bad point is that this shortening would shift the center of balance forward, which would likely delay yawing in soft tissue.

I haven't done a similar drawing for 6.8mm and 7mm, but going by this one, it looks as if you may be right about a "green" 6.5mm bullet not being heavy enough. Thoughts?

Tony Williams

07-08-2011, 06:36 AM

I haven't done a similar drawing for 6.8mm and 7mm, but going by this one, it looks as if you may be right about a "green" 6.5mm bullet not being heavy enough. Thoughts?

I think you've summed up the problems. Penetration into the case isn't necessarily an issue if the case capacity is big enough, but getting a good BC with less dense materials is difficult in small calibres; the length/diameter ratio could become a problem with stabilising such bullets.

stanc

07-08-2011, 09:44 AM

Okay, let me see if I have the whole picture right.

We need to get a worthwhile reduction in ammo weight, while having significantly better terminal effectiveness than 5.56x45 in close combat, with terminal effectiveness at long range -- and barrier penetration at all distances -- comparable (if not equal) to 7.62x51.

In addition, for psychological reasons muzzle velocity must be equal to that of 7.62x51 ball, when fired in barrels of the same length: 2700-2750 fps in a 20" barrel. Plus, it must be done using "eco-friendly" bullets, with steel and/or copper as core materials.

In order to get the necessary weight reduction, the cartridge case has to be of significantly smaller diameter and (probably) shorter length than for 7.62x51. On the surface, this appears feasible. The weight comparisons I did on the previous page show that 100 rounds of linked 7x46 provides a 25% weight reduction, and 6.8x43 cuts weight by 35%. IIRC, that's close to what the early LSAT goals were.

The bullet also must be substantially lighter than the standard 7.62 ball projectile, but be very streamlined, with a long ogive, so as to have a high BC for maximum downrange velocity and energy. Unfortunately, with a non-lead core, such bullets are extremely long, with undesirably high L/D ratios that may make a matching tracer (which is typically longer than the ball round) too long to be viable. Then there is the reduced powder capacity to contend with, too. If the bullet is shortened enough to solve those problems, then BC is greatly reduced. Plus, the lighter the bullet is made, the less effective it will be against both soft and hard targets.

I used to think this concept was doable, if just barely. But, after the last couple days, I'm beginning to think it may not be. :(

Tony Williams

07-08-2011, 10:46 AM

I think that with some compromises, we could get there, although lead-free ammo certainly makes it harder.

The barrier penetration doesn't have to match M80 at all ranges, just be closer to 7.62mm than it is to 5.56mm.

Similarly, I don't think that the muzzle velocity, or energy retention at long range, need to match M80 exactly as long as they are in the same ballpark, so that there will be little practical difference as far as the troops are concerned.

JASmith

07-08-2011, 01:34 PM

Take the 120 GMX shape, use voids up front to move the CG aft, different materials for improving penetration, etc., to reduce the weight to 100 gr and one gets a BC of .400 assuming the same shape factor.

This BC, coupled with a MV of around 2750 ft/sec for an 18.5" barrel (see http://ammoguide.com/?catid=456) and you track the 7.62X51 M80 fairly well for trajectory and wind resistance.

The bullet would have 90% of the sectional density of the M80, so would need some design effort (e. g., M855A1) to bring the barrier defeat and armor penetration up to the M80 level.

stanc

07-08-2011, 05:35 PM

The barrier penetration doesn't have to match M80 at all ranges, just be closer to 7.62mm than it is to 5.56mm.

Similarly, I don't think that the muzzle velocity, or energy retention at long range, need to match M80 exactly as long as they are in the same ballpark, so that there will be little practical difference as far as the troops are concerned.
It seems to me that barrier defeat and wound trauma must be equal to 7.62mm, or both the troops and the decision makers will object to replacing 7.62x51 with a less effective round. If we were still talking about replacing 5.56x45 only, that would be a different matter.

Also, if muzzle velocity (and to a lesser extent, downrange velocities) don't match M80, it won't pass Joe's "that looks about right" test. It isn't possible to match the retained energy with a lighter bullet launched at the same speed, so I'm not concerned with that. If terminal performance is as good as 7.62mm, energy figures shouldn't be of much consequence.

stanc

07-08-2011, 05:57 PM

Take the 120 GMX shape, use voids up front to move the CG aft, different materials for improving penetration, etc., to reduce the weight to 100 gr and one gets a BC of .400 assuming the same shape factor.

The bullet would have 90% of the sectional density of the M80, so would need some design effort (e. g., M855A1) to bring the barrier defeat and armor penetration up to the M80 level.
Using a void up front may be an option for the UK and Europe, but it's likely a no-go for the US Army, which seems pretty well locked into the exposed penetrator design of M855A1 and M80A1.

I don't know what different materials you're referring to. The only viable choices seem to be steel and copper. NAMMO's lead-free bullet is an FMJ with steel/steel core, and the RUAG projectile (like the US bullets) is steel/copper.

If I figured correctly, scale down the 130gr and 149gr versions of M80A1 to 7mm, and the resulting bullet weights are 101gr and 115gr, respectively. 6.8mm and 6.5mm versions are much lighter, IMO far too light to have a chance of achieving the necessary terminal performance.

JASmith

07-08-2011, 11:11 PM

You likely wouldn't do a linear scale -- let the length be long enough to get 95-105 grains and you're good to go!

BTW Non-concur on statement that "US is locked in on M855A1 style" -- it just happens to be the current fad. Hopefully it won't last as long as the M80!

Tony Williams

07-09-2011, 02:34 AM

It seems to me that barrier defeat and wound trauma must be equal to 7.62mm, or both the troops and the decision makers will object to replacing 7.62x51 with a less effective round. If we were still talking about replacing 5.56x45 only, that would be a different matter.

I don't think so. The official view of both the US and UK armies (which is what we need to address, whether or not we think it is right) is that 5.56mm is adequate to around 400m; if all future engagements were to be within this range, 7.62mm would promptly be returned to support status. So the main focus of an intermediate round in replacing 7.62mm must be its long-range performance. From that perspective, improved penetration and effectiveness at short range (compared with 5.56mm) is a secondary advantage - although I believe a very important one.

I went back and reread what little info is available on the 7mm UIAC. It turns out that the 2650 fps published muzzle velocity is for a 16-inch barrel. (I was under the mistaken impression that it was for a 20-inch tube.) That translates to ~2750 fps out of a 20-inch barrel, with a lead-core, 130gr bullet.

Cris was also talking about a heavy, long-range sniper load of 175 grains at 2,400 fps. I'll have to ask him about this - I'll be seeing him next week.

I guess that brings up the question, is a 25% reduction in ammo weight "good enough" to make the switch worth the costs?

Two different scenarios: if LSAT proceeds, the same cost would be involved whatever calibre is chosen. If LSAT fails, there is still a chance of introducing a new calibre (although the likelihood drops sharply) through stressing the "combined advantages":

1. To reduce the weight compared with 7.62mm ammunition without losing long-range effectiveness.
2. To improve the effectiveness compared with 5.56mm ammunition without the heavy recoil of 7.62mm.
3. To provide greater tactical flexibility, with all riflemen being equipped with weapons effective at all combat ranges.
4. To save on procurement, support and training by halving the number of different small arms acquired.