Grendel as a Universal Infantry Cartridge

[LR1955]

The bad news is that the US Army are going ahead with the carbine competition which everyone with an interest is 100% certain will resuilt in 5.56mm being confirmed and 90% certain that none of the competitors will be found to be so much better than the Product Improved M4 that the change will be worth it.

The good news is that it is confirmed that the JSSAST panel withdrew new funding from LSAT unless they can demonstrate downrange performance superior to the 5.56mm M249 LMG. It was announced publically that JSSAP will conduct a Caliber Study for LSAT in support of improved downrange performance. It will include 6.5mm as well as 7.62mm NATO.

Perhaps JSSAP would fund some experimentation and bullet development with 6.5mm Grendel?

Tony / Joe et. al:

This is why I say you must be able to offer something that can be proven to be a quantum improvement before someone will want to dump billions into re-tooling an entire industry.

I am not sure what can be done with a 6.5mm bullet that hasn't already been done or that would cost so much money to produce that it would bankrupt the nation. The bullet has been around for over a hundred years and has been thoroughly developed in terms of military, hunting, and competitive shooting. Unless you develop a powder that produces greater than 50% higher velocity with a 50% reduction in pressure, you won't get the speeds out of a 30 grain capacity 6.5mm cartridge that will allow it to compete with a 5.56 or 7.62 that doesn't need any more development.

LR1955

[Tony Williams]

I am not sure what can be done with a 6.5mm bullet that hasn't already been done or that would cost so much money to produce that it would bankrupt the nation. The bullet has been around for over a hundred years and has been thoroughly developed in terms of military, hunting, and competitive shooting. Unless you develop a powder that produces greater than 50% higher velocity with a 50% reduction in pressure, you won't get the speeds out of a 30 grain capacity 6.5mm cartridge that will allow it to compete with a 5.56 or 7.62 that doesn't need any more development.

The last time a 6.5mm military ball bullet was introduced was I believe in 1941 for the 6.5x55. Before that came the Japanese Arisaka Type 38 in 1905. A lot has happened since then - you only need to look at the M855A1 EPR.

Who said anything about a 30 grain capacity limit?

[stanc]

Tony / Joe et. al: This is why I say you must be able to offer something that can be proven to be a quantum improvement before someone will want to dump billions into re-tooling an entire industry.

Gene, why do you think it has to be a "quantum" improvement? When the Army switched from .50-70 to .45-70 to .30-40 to .30-06 to 7.62x51, those were all incremental improvements. Going to 5.56x45 was actually a quantum reduction in performance (although it did offer a quantum increase in number of rounds that a soldier could carry).

I am not sure what can be done with a 6.5mm bullet that hasn't already been done or that would cost so much money to produce that it would bankrupt the nation.

Why should it bankrupt the nation? Since 1865, the US military has changed rifle cartridges six times (seven, if the USMC/USN use of the 6mm Navy is counted), and managed to find the money to pay for it. Why should one more time be unaffordable?

The bullet has been around for over a hundred years and has been thoroughly developed in terms of military, hunting, and competitive shooting.

In terms of hunting and competition, yes it has. But it hasn't seen much development in terms of military bullets. The Japanese had a flat-base spitzer Ball, the Swedes a boat-tail spitzer Ball and AP, and Italy had a flat-base spitzer AP, but that's the extent of 6.5 military development. There are zero state-of-the-art 6.5mm military Ball projectiles available, and only a few lead-core FMJs.

Unless you develop a powder that produces greater than 50% higher velocity with a 50% reduction in pressure, you won't get the speeds out of a 30 grain capacity 6.5mm cartridge that will allow it to compete with a 5.56 or 7.62 that doesn't need any more development.

If you mean 6.5 Grendel, Tony is only advocating that for demonstration purposes. His concept cartridge would have somewhat greater powder capacity.

[LR1955]

Gene, why do you think it has to be a "quantum" improvement? When the Army switched from .50-70 to .45-70 to .30-40 to .30-06 to 7.62x51, those were all incremental improvements. Going to 5.56x45 was actually a quantum reduction in performance (although it did offer a quantum increase in number of rounds that a soldier could carry).

Why should it bankrupt the nation? Since 1865, the US military has changed rifle cartridges six times (seven, if the USMC/USN use of the 6mm Navy is counted), and managed to find the money to pay for it. Why should one more time be unaffordable?

In terms of hunting and competition, yes it has. But it hasn't seen much development in terms of military bullets. The Japanese had a flat-base spitzer Ball, the Swedes a boat-tail spitzer Ball and AP, and Italy had a flat-base spitzer AP, but that's the extent of 6.5 military development. There are zero state-of-the-art 6.5mm military Ball projectiles available, and only a few lead-core FMJs.

If you mean 6.5 Grendel, Tony is only advocating that for demonstration purposes. His concept cartridge would have somewhat greater powder capacity.

Stan et. al:

It is extremely evident that the military will not seriously consider a new round of ammunition unless it does increase hit and kill probabilities by a factor of two times what is available now. Tony just stated in reference to the M-4 that "90% certain that none of the competitors will be found to be so much better than the Product Improved M4 that the change will be worth it." Note the words 'so much better' than the PIP M4.

So, if you want to play the game today, you better prove beyond anyone's doubts that your cartridge will double hit and kill probabilities. And a round of ball ammo that costs $1.50 or $2.00 a cartridge will not be considered as an option. Not even for combat only. And look at the price of the more modern SRTA ammo. Not much less than standard ball.

If you want to get someone's attention -- double the hit and kill probability. Right now if you want to increase hit and kill probability you better double the velocity of the currently issued ball ammo. Or you better invent some sort of material for the bullet that gives it a BC of about 1.5. Or a combination of both powder and bullet which is more likely but still beyond our technology.

You see, very little has changed since the invention of smokeless powders. You aren't getting much more distance from a ball round of 7.62 NATO than you did from a ball round of 30-06 from WWI. So, you try to increase lethality via lower recoil, noise reduction, ergonomics, sighting systems, etc.

My point is that unless you can articulate a quantum increase somewhere -- the system will not even drop seed money into a project.

LR1955

[JASmith]

...My point is that unless you can articulate a quantum increase somewhere -- the system will not even drop seed money into a project.

LR1955

This is the point to articulating requirements. We start with a set of threshold requirements. In this case the threshold is a cartridge that is significantly lighter than the 7.62X51, but otherwise of the same performance. The objective, or "nice to have," or "what we're really looking for," statements lay out what a "quantum improvement, if any, means.

A major caveat is that the objective requirement statements need to be physically realizable. Done right, the process will tell us if there is a snowflake's chance in a warm place of demonstrating significant improvement.

Right now, substantial reductions in number for weight for both 5.56 and 7.62 is nearly a slam-dunk when plastic cartridge cases are demonstrated to be viable. Tony is advocating that the upgrade offers an opportunity to examine a change in the mix of calibers. Yes, he has a favorite, but in my view, we should consider it one of several options.

Another option is "do nothing." I am more than willing to accept this as our bottom line in spite of my interest in inventing new things. But the truth is we know there is at least some dissatisfaction and we have folks with the knowledge and energy to explore the options. Once completed, we will have a better appreciation about how much improvement is practicable.

In the interim, we can learn a lot about one of our favorite topics!

Cheers!

[bwaites]

Velocities for the Hornady loaded AMAX 123 out of my 28" barrel averaged 2720 FPS. From a 20" they averaged 2590. At 2590 they are still supersonic supposedly at 1223 FPS.

Velocities for the Scenar Factory load were 2740 and 2600 respectively. At 2600 they would be still supersonic at 1257 FPS.

Using G7 drag numbers drops the Lapua by 57 FPS, but even so, its still supersonic at 1000.


Those are both factory loads, with powders not available to the public at this point, and real world testing is needed to confirm those numbers. I intend to try those loads at 1000 this year.

That said, I don't think either bullet is a real world bullet for military use, and some FMJ with a similar BC would be needed to carry that banner.

[LRRPF52]

Bill,

Did you mean that with a muzzle velocity of 2590 fps, the 123 AMAX is still supersonic at 1000 yds, (at 1223 fps)? Same for the Scenars? Those are some pretty good velocities. Any pressure signs on the brass?

Thanks for the info.

LRRPF52

[bwaites]

Bill,

Did you mean that with a muzzle velocity of 2590 fps, the 123 AMAX is still supersonic at 1000 yds, (at 1223 fps)? Same for the Scenars? Those are some pretty good velocities. Any pressure signs on the brass?

Thanks for the info.

LRRPF52

LRRPF52, yes, if I recall correctly, sea level speed of sound is 1126 FPS under standard atmospheric conditions, so both bullets should still be supersonic at those speeds.

No pressure signs, and both are the factory loads. I pulled ammo out of brand new boxes, shot it through my 28" and then immediately through a 20" my friend owns. The Hornady was from the first batch of Hornady ammo from last year.

I'll have some second run ammo this next week and will chrono it.

ES for the Scenars was 35 FPS, and for the Hornady was 26 FPS. Not bad for factory loads. I also ran some hand loads, with XBR under 107 Sierras, and they were at 2790 FPS with ES of 19. I got close to factory speeds with TAC at 2712 and ES of 21 under AMAX 123's as well. Scenar 123's over N133 ran 2642 but had a much larger ES of 48.

None of the loads did anything unusual, and there were no apparent pressure signs, but I don't put much faith in pressure signs in gas guns. I've seen broken bolts with perfectly normal looking brass in both Grendels and 5.56's.

[stanc]

Velocities for the Hornady loaded AMAX 123 out of my 28" barrel averaged 2720 FPS. From a 20" they averaged 2590. At 2590 they are still supersonic supposedly at 1223 FPS.

Velocities for the Scenar Factory load were 2740 and 2600 respectively. At 2600 they would be still supersonic at 1257 FPS.

Thanks for those numbers, Bill.

That said, I don't think either bullet is a real world bullet for military use...

No doubt about it.

...and some FMJ with a similar BC would be needed to carry that banner.

Trouble is, that doesn't seem possible. With the environmental laws prohibiting lead in bullets, it looks to me like to get a circa 0.54 BC with steel (or steel and copper) as core material would make a bullet with an impractical L/D ratio. Barnes' nicely-streamlined 110gr solid is about 4.7:1, and only has a 0.45 BC.

Make an eco-friendly FMJ or T3 bullet, with L/D of 5:1, and weight probably would not exceed 110gr. Which makes it seem likely that BC would be ~0.45, also.

On the subject of FMJs, what are the chances of you shooting the 120gr Normas (in 20" barrel) to 1000 yards?

[LRRPF52]

None of the loads did anything unusual, and there were no apparent pressure signs, but I don't put much faith in pressure signs in gas guns. I've seen broken bolts with perfectly normal looking brass in both Grendels and 5.56's.

I'm not so concerned about broken bolts, since that is a design failure the guys made when they scaled down the AR10 to the AR15 and went whimpy on the bolt geometry for the .222 Special/.223 Remington. I am more concerned about case failures from over-pressure. Both the Grendel and AR15 in 5.56 need stronger, beefier bolts closer to what an AR10 is.

LRRPF52

[bwaites]

Thanks for those numbers, Bill.

No doubt about it.

Trouble is, that doesn't seem possible. With the environmental laws prohibiting lead in bullets, it looks to me like to get a circa 0.54 BC with steel (or steel and copper) as core material would make a bullet with an impractical L/D ratio. Barnes' nicely-streamlined 110gr solid is about 4.7:1, and only has a 0.45 BC.

[The other issue with solid bullets is that they do not compress as nicely as lead core bullets in the bore. I've shot a lot of the Barnes bullets, and you have to be very careful to avoid pressure issues. Along with that, I not sure they will tumble as readily as lead/copper bullets do. I've shot them through wood, and they look like they could be reloaded!] Bill

Make an eco-friendly FMJ or T3 bullet, with L/D of 5:1, and weight probably would not exceed 110gr. Which makes it seem likely that BC would be ~0.45, also.

On the subject of FMJs, what are the chances of you shooting the 120gr Normas (in 20" barrel) to 1000 yards?

I only have a very small supply of them, provided by Variable to do some steel penetration testing. I would be happy to try them at 1000, if I could get a 100 or so to work up a decent load.

[bwaites]

I'm not so concerned about broken bolts, since that is a design failure the guys made when they scaled down the AR10 to the AR15 and went whimpy on the bolt geometry for the .222 Special/.223 Remington. I am more concerned about case failures from over-pressure. Both the Grendel and AR15 in 5.56 need stronger, beefier bolts closer to what an AR10 is.

LRRPF52

I've discussed this issue at length with Bill Alexander and several other AR guys. They all are in agreement that if you beef the bolt up, you'll create a failure somewhere else, and that failure might be much more dangerous to the user than a bolt failure. As it is, when the bolt fails, any damage tends to go out the bottom of the mag well, which is a generally safe place to go, versus back toward the user, or out the sides towards friendlies.

I've yet to blow up a Grendel case, and I have cases with 20+ reloads on them. I've had neck splits, but that is a factor of working the necks so much, I think.

[JASmith]

...it looks to me like to get a circa 0.54 BC with steel (or steel and copper) as core material would make a bullet with an impractical L/D ratio...with L/D of 5:1...

Does anyone know the basis for the L/D = 5 being a practical length limit?

I did a quick perusal of the JBM length tables (http://www.jbmballistics.com/ballist.../lengths.shtml) and found several in the range of 5.4<L/D<5.8 so it would appear that L/D = 5 is not a hard limit.

[stanc]

I only have a very small supply of them, provided by Variable to do some steel penetration testing. I would be happy to try them at 1000, if I could get a 100 or so to work up a decent load.

Midway shows them in box of 100 for $33.99

http://www.midwayusa.com/viewProduct/default.aspx?productNumber=464397

If you order a box, I'll be happy to reimburse you.

[bwaites]

stan,

No need, I'll see if I can get any. If I can get them up to 2700 FPS, they should go transonic right at 1000 yards.