New Army "Caliber Configuration Study"

[stanc]

Mybe it wasn't the X15, the one I saw was plastic and clear, I was told it held 100 rounds...

The only mag I can think of which seems to fit that description is the MWG 90-rounder.

http://www.youtube.com/watch?v=JUtRBV8VBaY

I think something like a 6.5 IAR would work well because the DMR and the Auto gunner are the same guy...
I have never fired a Grendel in Burst or Full auto so I'm not sure how it would act (Heat issues, feeding issues etc) but I can tell you that I'm yet to find a 26 round mag to feed correctly 100% of the time.

Yes, I think combining DMR and IAR in the same gun/shooter might be a good way to go.

Grendel magazine reliability appears to be inconsistent. Some people report problems, while other individuals claim flawless functioning. Regardless, that's the only hi-cap mag available if somebody wants to build and demonstrate a 6.5G IAR.

Forum member "Variable" shoots 6.5G full-auto. IIRC, he's never reported any issues. A few years ago, he wanted to make a Grendelized Colt LMG, but was unable to get a super-heavy 6.5G barrel.

http://www.youtube.com/watch?v=tLX2zauiI38

[Tony Williams]

Yes, I think combining DMR and IAR in the same gun/shooter might be a good way to go.

Some of the suggestions emerging in this thread - it's great to get such info, guys, keep it coming - remind me of this: http://www.quarry.nildram.co.uk/futu...all%20arms.htm

[joker31]

I have worked with some of the best in the business and I can tell you, if you can get a reliable system thats 10-15% less effective, it doesnt matter, it will have to be a huge difference to make the change worth it. The guys I worked with would run battle drills to build muscle memory for hours, I have been on missions that were mocked up on a sound stage type building where each guy knew how many steps he would take to each point and how many stairs there were in each portion of the building etc, so yes things are very hard to change because they are drilled into your body, stuff like malfunctions are felt before they are seen, so all of this will have to be re-learned and retrained so, any change in platform is out of the question for some commands.

I think the changes need to happen to the sidearm first because the beretta is a decent weapon but there are others out the that are more effective and require less training, in my command everyone had a pistol, I think anyone who goes outside the wire should have one and the Army brass are starting to see it that way too. After the crap that went on with the Jessica Lynch thing and countless others where capture was a possibility the pistol became a defensive weapon and the rifle was an offensive weapon by definition after the reports came out. Thats when the big push for pistols came out.

[joker31]

M27 question: Anyone know where these pictures of chopped rear sights are coming from for the IAR? I only have seen 2 sights, 1 is the Diopter sight (Drum) and the other is the Knights lollypop sight, I keep seeing a sight thats cut off on the left side, kinda weird looking.

[montana]

A lot of great perspectives and info here guys, "eye opening". A lot has changed since I was a pup.

[stanc]

I have worked with some of the best in the business and I can tell you, if you can get a reliable system thats 10-15% less effective, it doesnt matter, it will have to be a huge difference to make the change worth it. The guys I worked with would run battle drills to build muscle memory for hours, I have been on missions that were mocked up on a sound stage type building where each guy knew how many steps he would take to each point and how many stairs there were in each portion of the building etc, so yes things are very hard to change because they are drilled into your body, stuff like malfunctions are felt before they are seen, so all of this will have to be re-learned and retrained so, any change in platform is out of the question for some commands.

Would that also apply to a change in size? The cartridges being developed by USAMU and other entities are too long to fit the M4 mag length. Could a new carbine that's a bit larger than the M4, but otherwise identical, be acceptable? I'm thinking something like the DPMS GII (bottom gun in photo).



Of course, such "general purpose cartridges" will need magazines substantially larger than for 5.56mm, and weight of loaded 30-rd mags will be ~50% heavier.

[BluntForceTrauma]

Enjoyed your article Tony. Reading the U.S. list of requirements makes the 6.5 Grendel face-palmingly obvious to me! I don't favor a 6.5x45 because I think the 6.5x39 Grendel is already at the top range of recoil for mass recruits and I like that it fits in the existing AR series and, in general, the more compact the better.

You also made a strong argument for a bullpup; when we get a helical tube-magazine that makes it possible to go prone without a clumsy box magazine under one's armpit, I'm onboard!

John

[stanc]

Thought this might be of interest to the group:

Now with CLAWS and LDAM everything has changed again. For a long time, the US Army was obtuse in its refusal to consider alternate calibers. The increasing re-adoption of 7.62mm and the serious issues with 5.56mm M855A1 EPR have changed that. ARDEC seems to be of the view that 5.56mm has reached its maximum development potential. This is good news.

NATO seems to be on a critical path to replacing its small arms between 2020 and 2025, so I am not expecting any decision on a new caliber within the next 2-3 years. That said, the work done by the US Army Marksmanship Unit at Fort Benning to develop custom ammunition types in 6.5mm and 6.8mm independently validates what Tony, ARDEC and every other caliber study over the last 100 years has recommended: If you want lead free ammo, 6.8mm is right way to go. If you want lead ammo, then 6.5mm will suffice. Both rounds comfortably exceed 7.62mm NATO range and retained energy performance figures when fired from guns with same length barrels. Interestingly, US AMU stipulates that you need a case with a capacity of 40 grains of water to propel a 7g or 8g projectile so that it outperforms 7.62mm to 1,000 metres.

Having seen test results, a 7g or 8g bullet in 6.5mm or 6.8mm can do everything a 7.62mm bullet can do, but shoots flatter, further, and faster with less wind drift and less recoil. The improvement in hit probability versus 7.62mm is astonishing. Such a round could easily be fielded in rifles and machine guns at squad level and would be a better solution than both 5.56mm and 7.62mm. There is no doubt in my mind about this. Forget the the weight argument (even though a 6.8 x 45 mm cartridge would only weigh 17-18 g) this is all about shooting effectiveness.

http://forums.delphiforums.com/autog...s/?msg=5074.20

[BluntForceTrauma]

If you want lead free ammo, 6.8mm is right way to go. If you want lead ammo, then 6.5mm will suffice.

First, I presume they're talking about a high BC 6.8. Everyone knows any 6.8 under about 120 grains is a non-starter. Second, Stan, do you happen to know what he means by this, or do I need to dig up the source?

so that it outperforms 7.62mm to 1,000 metres.

Again, arbitrary. Being an iconoclast, I ask "Why?" They answer, "Uh, because that's what the .308 does." "Why?" "Uh, because that's what the .30-06 did." "Why?" "Uh, because we need massed rifle volley fire at 2000 yards. Duh!"

Put your development money into long-range, air-burst grenades instead of the last war. Or, should I say, the wars of the previous century.

John

[stanc]

First, I presume they're talking about a high BC 6.8. Everyone knows any 6.8 under about 120 grains is a non-starter. Second, Stan, do you happen to know what he means by this, or do I need to dig up the source?

John, I do know. He does not mean 6.8 SPC. Think something like Cris Murray's 7x46 UIAC, except with high-BC .277" bullet. The consensus on Tony's MG&A forum is that lead-free .264" bullets probably won't be heavy enough to provide acceptable terminal effects.


.276 Pedersen, .270 British, 7x43 British, 7.62x51 NATO, 7x46 UIAC, 6.5x38 Grendel

Again, arbitrary. Being an iconoclast, I ask "Why?" They answer, "Uh, because that's what the .308 does."

You're correct as to the why, but I disagree that it's arbitrary. In the absence of information to the contrary, I think it is reasonable to expect the military will want at least 7.62 performance in a replacement for that round, and that's been the prevailing view of GPC proponents.

I also thought that way, but the CLAWS and LDAM programs made me re-evaluate the issue. With LDAM seeking a replacement for 7.62 NATO as the MMG caliber, I now think that it may not be necessary to match 7.62 performance in a new cartridge for carbines, DMRs, and LMGs.

IMO, it all depends on what performance the military decides they want, and what weight penalties they're willing to accept.

Put your development money into long-range, air-burst grenades instead of the last war. Or, should I say, the wars of the previous century.

The military is putting money into airburst grenades. But, as LRRPF52 noted, ABGLs can't replace rifles and machine guns (at least, at this stage), so some development efforts will have to also go into conventional bullet-firing weapons.

[nincomp]

John, you can see where Stan came up with the larger case than the current 6.8's buried in the quote from Guardsman26's: " Interestingly, US AMU stipulates that you need a case with a capacity of 40 grains of water to propel a 7g or 8g projectile so that it outperforms 7.62mm to 1,000 metres."

Although I am usually suspect of round numbers like "1,000 meters," it turns out that the range of the 7.62x54 weapons (like the PKM) is close to that. Joker31 wanted an MMG that would at least out shoot the PKM. The cartridges mentioned above should at least match the range of a PKM.

I do not want to start the definition wars again, so there would be a relatively lightweight MG for our dismounted troops that would match the range of the opposing 7.62x54 ones.

Although I may be misreading Joker's post, it seems that our 7.62x51 weapons do not match the 7.62x54's. I would imagine that this is why such things as the .338 Norma Mag have been mentioned. Whatever is used, I hope that it will not be hobbled by short ogive projectiles (like the 5.56, 7.62N, and even to some extent, the 338 LM).

[BluntForceTrauma]

propel a 7g or 8g projectile so that it outperforms 7.62mm to 1,000 metros. . . . The cartridges mentioned above should at least match the range of a PKM.

7grams is 108grains and 8g is 123gr. The 6.5 Grendel ALREADY matches the "range" — the external ballistics — of the PKM. The question is whether the terminal performance of its 123gr bullet is acceptable relative to the PKM's 147gr bullet. And that terminal "acceptability" is somewhat arbitrary.

I'm comfortable with a 65G LMG having 1452 rounds for the same weight as a PKM's 1000 rounds. I say this because the external ballistics are a match and because I think, terminally, a 6.5mm 123gr in the head is gonna ruin your day almost as much as a 7.62mm 147gr in the head.

John

[stanc]

Although I may be misreading Joker's post, it seems that our 7.62x51 weapons do not match the 7.62x54's.

Other people have said this, too. I don't know on what this claim is based.

Muzzle velocities of 7.62x51 and 7.62x54R are both ~2800 fps.

147gr M80 Ball has a 0.397-0.418 BC, according to the sources I checked a few years ago when running ballistics tables.

148gr LPS Ball has a 0.377 BC, according to http://7.62x54r.net/MosinID/MosinAmmo025.htm

If that data is correct, our M240 should outrange the enemy's PKM.

[stanc]

external

When using HPBT match bullets, 6.5G may match trajectory and drift of 7.62x54R FMJ ball. The question is, how would a 6.5G 108gr Ball load compare?

I very much doubt that you'll be able to get anywhere close to matching the BC of Scenars and MatchKings in a service grade ball projectile.

The question is whether the terminal performance of its 123gr bullet is acceptable relative to the PKM's 147gr bullet.

Why do you keep talking about a 123gr bullet, John? That weight appears to be feasible only with a lead-core bullet, and the military is moving to lead-free projectiles for general-issue, ball ammo.

[BluntForceTrauma]

On the contrary, I have no doubt a 6.5mm ball round can match the BC of a SMK. Why? Look at the 7.62N 147gr FMJ. Meplat is already very small, no bigger than an HPBT. Ogive is already very sleek, damn near secant. If they could do it with a 50-year-old FMJ I have no doubt they can do it today.

I hear you on the lead-free issue. Many of my calculations would need to be redone. My position on the issue is that if the U.S. military doesn't hire some serious people real soon and persists in its politically-correct sensitivity training, women in front-line combat, and environmentally-approved weapons, we've got bigger problems than a new small arms cartridge.

I guess I'm assuming that in a real shooting war with China that, somehow, the grown-ups will be back in charge and green bullets will take a backseat to the steely-eyed dealing of death.

John