New Cartridge Developments and Implications for Dismounted Infantry Soldiers

[stanc]

What's amazing to me is that my dad and other relatives carried either the Garrand or .30 carbine all over WII and got the job done. Countless soldiers carried the 30:06 all over with a 9+ lb rifle plus the gear. what I especially don't understand about our military is why they want to stay with a varmint round. I know it's a NATO round etc, but putting combatant down quickly vs multiple shoots doesn't make sense.

The 5.56mm M4 is the modern equivalent of the .30 M1 carbine, which reportedly often required multiple hits to stop an enemy soldier.

What I don't understand is why today everybody (but me ) has proposed alternative cartridges only in 6.5mm, 6.8mm and 7mm. Why, them's all furrin calibers.

6mm is a uniquely American military caliber. Japan, Norway and Sweden had 6.5mm, China had 6.8mm, Spain had 7mm, but only the United States has ever adopted and fielded 6mm rifles and machine guns.

[JASmith]

...6mm is a uniquely American military caliber. Japan, Norway and Sweden had 6.5mm, China had 6.8mm, Spain had 7mm, but only the United States has ever adopted and fielded 6mm rifles and machine guns.

You know, I never realized that!

Thanks for the insight!!!

[Tony Williams]

But 6.8mm is also .270, which has an honourable place in US commercial rounds!

[LRRPF52]

What's amazing to me is that my dad and other relatives carried either the Garrand or .30 carbine all over WII and got the job done. Countless soldiers carried the 30:06 all over with a 9+ lb rifle plus the gear. what I especially don't understand about our military is why they want to stay with a varmint round. I know it's a NATO round etc, but putting combatant down quickly vs multiple shoots doesn't make sense. Don't even get me started on the 9mm vs the 45 acp! Once again a heavier bullet will do more damage as well stop a vehicle.

There's nothing really wrong with 5.56 NATO. I'm a self-admitted 5.56 Nazi, so you can ridicule me all you like. I've seen what it does, and I'm more than impressed with it. I've never seen a clean 5.56 injury or fatality-they have all been ugly. For dismounted riflemen, it's an excellent cartridge with formidable performance characteristics. Whether I'm carrying an M4 or a 7.62 NATO rifle, or even a 7.62x39 weapon, I'm not going to be shooting one round, then assessing target feedback. I'm going to place continuous well-aimed fire into the target until it is squirming in the dirt, and then shoot again if possible.

I wouldn't assess the bulk of US military success in WWII on the small arms they had then, because the Germans had several better weapon systems when looking at the MG42, MG34, G41, and later the Stg44, but those really were put to the most use on the Russian and Eastern European front. Our dismounts were really policing up what was left of only 1/3 of the Wermacht back in Germany, after being bombed tortuously by thermite munitions from B-17's & B-24's. We literally burned scores of German cities to the ground in hellish infernos that often reached unearthly temperatures. The same thing was done to Japan.

I wouldn't attribute the small arms mix we had as a decisive factor in any US victories in Central Europe, speaking from a holistic picture of warfare in that conflict. Had we been fighting the two-thirds of the German Army that was on the Russian front since 1941, it would have been an entirely different outcome. Millions of Russians lost their lives in numerous spearheads and campaigns from the German Blitzkriegs, which has been adopted by the US for combined-arms warfare since the Germans pioneered it.

5.56 NATO is not where we have a weakness in the current small arms mix. Even though it isn't an intermediate cartridge in the idea behind 7.62x39 and 7.92x33, the SCHV concept has proven itself an excellent component as far as small arms go for dismounted riflemen, and even support personnel. The real area for improvement is in our Light Machineguns, General Purpose Machineguns, and sniper rifles. As you might have seen before in the discussion, I'm a huge proponent of fixing this area of small arms chambering from the 7.62 NATO to something lighter, with equal or better ballistics.

LRRPF52

[JASmith]

There's nothing really wrong with 5.56 NATO....

...The real area for improvement is in our Light Machineguns, General Purpose Machineguns, and sniper rifles. As you might have seen before in the discussion, I'm a huge proponent of fixing this area of small arms chambering from the 7.62 NATO to something lighter, with equal or better ballistics.

Those are useful confirmations of where Tony's understanding has moved to. We all (especially yours truly), learn with time, experience and improved knowledge.

Where I continue to be stuck is "How do we treat the enormous investment in vehicle-mounted 7.62's?" By the time you add up the machine guns on HMMV's and other wheeled vehicles, light armored vehicles, plus mini-guns on helicopters and AF gunships, you have an enormous stock of weapons. One could speculate that the mounted application also accounts for the bulk of the 7.62X51 ammunition consumption.

Proponents of the mounted application will likely advocate for improved 7.62X51 ammunition instead of a newer, lighter cartridge and caliber combination. Further, the 147-150 grain bullet was arrived at to reduce the recoil in shoulder-fired applications more than, I believe, from keeping equipment from being shaken apart.

Should we then advocate both the lighter, still highly capable cartridge while pointing out that eliminating the 7.62X51 from the dismounted role creates an opportunity for adopting a heavier, more effective bullet for the mounted role?

[stanc]

Where I continue to be stuck is "How do we treat the enormous investment in vehicle-mounted 7.62's?" By the time you add up the machine guns on HMMV's and other wheeled vehicles, light armored vehicles, plus mini-guns on helicopters and AF gunships, you have an enormous stock of weapons.

A very relevant question. I don't view the guns on wheeled vehicles as a problem. They are just infantry machine guns on pintle mounts. And, since the 5.56 M249 is often used for that purpose, it seems clear that caliber doesn't have to be 7.62x51.

Armored vehicles and aircraft may be another matter. Although in theory the 7.62 weapons could be converted to the new round, the reality is that it would require considerable expense and effort to convert not only the guns, but also the feed systems and (perhaps) the stowage bins. The benefit of increased number of rounds for a given weight/space might not be deemed worth the cost.

Which means you'd end up with a three-caliber system, and that's been opposed by the leadership at least as far back as 1970, when the 6mm SAW round was dropped in favor of an improved 5.56x45 loading.

Should we then advocate both the lighter, still highly capable cartridge while pointing out that eliminating the 7.62X51 from the dismounted role creates an opportunity for adopting a heavier, more effective bullet for the mounted role?

If you mean a heavier, more effective cartridge, I doubt that would fly. They already use .50 cal for some vehicle/aircraft applications. I think that anything in between 7.62 and .50 would be viewed as more gun than needed for the 7.62 use, and "not enough" gun to replace the .50 BMG.

Plus, even if it were to be argued that a new machine gun in caliber intermediate between 7.62 and .50 could replace both on aircraft and armored vehicles, then you've at least doubled the difficulty in getting the new infantry caliber adopted. Getting one new cartridge fielded will be hard enough, but to get two such changes at the same time?

[JASmith]

Should we then advocate both the lighter, still highly capable cartridge while pointing out that eliminating the 7.62X51 from the dismounted role creates an opportunity for adopting a heavier, more effective bullet for the mounted role?

Stan, a bullet is different from a cartridge. As you know there is already activity to get a new bullet for the 7.62X51. The opportunity is that folks might be able to allow that balance to move away from shoulder fired weapons in optimizing that new bullet and consider requirements derived only from vehicle and aircraft mounted roles. This might mean, e. g., a 165 grain bullet for the 7.62X51 that could be more effective at barrier defeat at the longer ranges.

[bwaites]

If you want barrier penetration, the 7.62x51 is plenty capable of launching a 200+ grain bullet at appropriate velocity to do so. With some of new powders, it will be a very good round for that application. If you go to strictly mounted use, you can even load it a bit longer and get back some of the lost powder space.

The .gov can order enough rounds that the new powders would be cost comparable with bulk powders, now, too.

[stanc]

Stan, a bullet is different from a cartridge.

Of course. In the context of what you wrote, I wasn't sure that "bullet" is what you really meant.

As you know there is already activity to get a new bullet for the 7.62X51. The opportunity is that folks might be able to allow that balance to move away from shoulder fired weapons in optimizing that new bullet and consider requirements derived only from vehicle and aircraft mounted roles. This might mean, e. g., a 165 grain bullet for the 7.62X51 that could be more effective at barrier defeat at the longer ranges.

I don't know if they've looked at anything heavier than 149 grains for M80A1, but yes, a 165gr bullet might have better hard target penetration at long range.

However, such a heavy (unleaded) bullet would be very long, and occupy a not-insignificant amount of powder space in the case. That would reduce muzzle velocity, and adversely affect penetration at long range.

[stanc]

If you want barrier penetration, the 7.62x51 is plenty capable of launching a 200+ grain bullet at appropriate velocity to do so. If you go to strictly mounted use, you can even load it a bit longer and get back some of the lost powder space.

A 200+ grain "eco-friendly" bullet would be extremely long for caliber, and likely require barrels with a faster rifling twist. Even loaded long, a lot of powder space would be lost. Plus, a long loading might require gun modifications, something to be avoided, if at all possible.

[bwaites]

So we still need eco-friendly?

I agree, its tougher to do, but its still doable. In fact, a solid copper bullet would work. 180 grain Barnes with a BC or .473 can be loaded easily to 2700 FPS with easily available powders. Using the newer Superperformance powders, I'd bet you could get over 2800 out of them, at standard length.

Bumping to 200 grains loses several hundred feet per second, but is doable, with 2600 FPS velocities at standard length.

[stanc]

So we still need eco-friendly?

I reckon so. I haven't seen any sign of the need being dropped.

I agree, its tougher to do, but its still doable. In fact, a solid copper bullet would work. 180 grain Barnes with a BC or .473 can be loaded easily to 2700 FPS with easily available powders. Using the newer Superperformance powders, I'd bet you could get over 2800 out of them, at standard length.

I doubt that solid copper is a viable option. For one thing, it probably would lack hard target penetration, judging by your photo of the Barnes 6.5mm 110gr solid fail to penetrate (3/8"?) mild steel plate.

Would probably need a "stretched" M80A1. The attached pic shows 149gr, 165gr and 200gr versions. If I'm not mistaken, the very long bearing surface would negatively impact muzzle velocity and barrel wear.

Going by the increased penetration claimed for 5.56mm M855A1, the 149gr M80A1 ought to give substantial improvement, perhaps comparable to a heavier version at slower MV.

[JASmith]

So we still need eco-friendly?

I agree, its tougher to do, but its still doable. In fact, a solid copper bullet would work. 180 grain Barnes with a BC or .473 can be loaded easily to 2700 FPS with easily available powders. Using the newer Superperformance powders, I'd bet you could get over 2800 out of them, at standard length.

Bumping to 200 grains loses several hundred feet per second, but is doable, with 2600 FPS velocities at standard length.

I've looked at the loaded ammunition offered for the TTSX and compared with that for the 168 gr. Game King:

Barnes 168 gr TTSX Muzzle Velocity: 2680 fps
Federal 165 gr TSX Muzzle Velocity: 2700 fps
Federal 165 Sierra Game King Muzzle Velocity: 2700 fps

I've also looked at the load recommendations by Barnes and found that they suggest using the same data for TTSX as used for TSX and MRX bullets. The velocities are consistent with the commercial ammunition.

Chances are that the perfomance boost available with the newest powders will perform in line with the 100-150 ft/sec claimed by Hodgdon. Hornady offers a Superformance load for the 168gr GMX bullet with a muzzle Velocity of 2750 fps. It is true that steel is slightly less dense than copper and the powders may not deliver all that is promised, the difference isn't enough to make Bill's velocity estimates change by a significant amount.

In any event, we know that we can get 2750 with a 168 gr TTSX. Removing the plastic nose plug and replacing with an appropriate length hardened steel penetrator won't lengthen the bullet by an appreciable amount, particularly if the meplat is the same size as that of the TSX.

Hence, I would tend to go with Bill's estimates as the optimistic upper bound and with the demonstrated 2750 for the 168 gr as the lower bound.

I also found loads in a respected reloading site (Ammoguide.com) listing velocities in excess of 2700 ft/sec for the XLC coated bullet.

[JASmith]

...Would probably need a "stretched" M80A1. The attached pic shows 149gr, 165gr and 200gr versions. If I'm not mistaken, the very long bearing surface would negatively impact muzzle velocity and barrel wear...

Copper fouling also becomes significant, which is one of the reasons you see more and more banded bullets.

This is a work-around that may be viable in military bullets when using modern fabrication machinery.

Making a more precise statement -- you can still get the long bullet and without getting a long bearing surface. Hence the longer, heavier "eco-friendly" (read PC) bullets would likely work just fine!

[stanc]

Copper fouling also becomes significant, which is one of the reasons you see more and more banded bullets.

This is a work-around that may be viable in military bullets when using modern fabrication machinery.

Trouble is, banded bullets are unlikely to be used by the Army. The jacketed, exposed penetrator (M855A1) design was chosen because it could be made on the existing machinery at Lake City. Any new caliber would certainly face the same requirement.

Making a more precise statement -- you can still get the long bullet and without getting a long bearing surface.

Yeah, but in addition to the manufacturing issue, there's also the question of whether or not a matching tracer would be feasible.