Optimized Caliber Proposal

[68WJ]

The best feature of the 6.8 is terminal performance from a carbine within engagement distances that typical soldiers can effectively make hits (backed by gel tests and supported by deer in freezers). However, a 6mm bullet has been a proven winner in hunting camps too and should perform admirably when pushed to good velocities. Will it have feeding issues though due to the larger shoulder and what is the optimum barrel length? These are things that can be vetted during testing, but I definately still like the cartridge for sporting purposes.

[stanc]

The best feature of the 6.8 is terminal performance from a carbine within engagement distances that typical soldiers can effectively make hits (backed by gel tests and supported by deer in freezers).

There are three problems with that statement:

a. The deer have been shot with bullet types very unlikely to be used by the Army, which makes that part irrelevant to military use of 6.8 SPC.

b. SSA gel tests of an M855-type 6.8 load a few years ago showed results little better than 5.56 M855, according to Art Kalwas. Plus, there is no public data on gel tests conducted with M855A1-type bullets in 6.8 SPC, or if in fact, any were ever even built and tested. (All we have in regard to the ARDEC tests of alternate calibers are third-hand reports that .277 bullets did better than .257 and .243 projectiles, but I've seen no mention of either bullet weights or the cartridges used.)

c. Wound profile in gelatin is only one factor in selecting an optimum cartridge for military use. There are other things to be considered, such as trajectory, wind drift, danger space, and tracer performance, to name some. Even if 6.8 is the best choice for carbines, it might not be the best option for LMGs or DMRs.

However, a 6mm bullet has been a proven winner in hunting camps too and should perform admirably when pushed to good velocities. Will it have feeding issues though due to the larger shoulder and what is the optimum barrel length?

There is so little difference in the shoulder that I can't imagine it'd cause any feeding difficulties. As for barrel length, the Army will undoubtedly use whatever length deemed appropriate to the mission, whether or not it's optimum for the cartridge (as they did in going from the 20" M16 rifle to the 14.5" M4 carbine).

These are things that can be vetted during testing, but I definately still like the cartridge for sporting purposes.

Yeah. If 6x41 were available as factory ammo, I'd jump on it without hesitation. Hmm. It suddenly occurred to me that maybe the reason I never bought a 6.8 or 6.5 rifle is because subconsciously I realized neither one was what I really wanted...

[HTR]

There are three problems with that statement:

I only see two problems with your statements here, Stan.

a. The deer have been shot with bullet types very unlikely to be used by the Army, which makes that part irrelevant to military use of 6.8 SPC.

Since caliber does not solve performance problems in itself, the military is finally realizing that bullet construction is much more important to lethality and the possibility of multiple modes of function. If I'm wrong, then why is there a move already afoot to field the OTM, the SOST / TOTM? If nothing else, these developments show that the same bullet types killing deer and hogs so effectively, are already getting both recognition and being issued as we speak. Perhaps not ubiquitously, but they are on the radar and in the plans for the future. IMO, the simplest thing they could do to improve performance is specifically to cease using non-expanding bullets. All-copper, or TOTM works better for multiple purposes than does a FMJ or penetrator type bullet.




b. SSA gel tests of an M855-type 6.8 load a few years ago showed results little better than 5.56 M855, according to Art Kalwas. Plus, there is no public data on gel tests conducted with M855A1-type bullets in 6.8 SPC, or if in fact, any were ever even built and tested. (All we have in regard to the ARDEC tests of alternate calibers are third-hand reports that .277 bullets did better than .257 and .243 projectiles, but I've seen no mention of either bullet weights or the cartridges used.)

If I were shooting anything alive, I would not preferentially choose a "M855 type bullet," in any caliber. Why waste time testing something that we already know sucks? If you put that bullet, eschewing better designs, in 5.56, 6.8 or 6.5 Grendel, then they all would be worse off. IMO, the best way to castrate / ruin the performance of any caliber or cartridge design, is to use the poor M855 design for anything. I have many thousands of hours in the field and thousands of AAR's on dead things and I can tell you that the M855 "penetrator" style bullet is the worst design of any I've used. I have shot car doors, gel, and animals and my results agree with most military testing. I must say, I also liked the performance of my 6MM Remington on many of the same things. The 6mm 85 TSX was awesome, and the Hornady Spire point in 6mm was also devastating. I sure hope nobody wants to put an FMJ or M855 type bullet in the 6 X 41. Please don't.....

c. Wound profile in gelatin is only one factor in selecting an optimum cartridge for military use. There are other things to be considered, such as trajectory, wind drift, danger space, and tracer performance, to name some. Even if 6.8 is the best choice for carbines, it might not be the best option for LMGs or DMRs.

Now, with this, I do agree. 6 X 41 does equal the bullet weight of the best 6.8 bullets (~95 grains) and much better BC. Therefore, if the velocity were equal (which it seems like it will be close) then the 6 X 41 could be well-suited to both SBR's, SMG's and alternatively, DMR with long barrels. The thing that remains to be seen is if it can reach 6.8 velocities in 8, 10, 12 or 14.5" barrels. Realistically, do you think we are likely to ever see the Army go with one cartridge for all its various squad rifles? I'm asking because it seems that the presence of M14's and other 7.62 rifles indicates that has been the stop gap measure thus far, for performance gaps.

There is so little difference in the shoulder that I can't imagine it'd cause any feeding difficulties. As for barrel length, the Army will undoubtedly use whatever length deemed appropriate to the mission, whether or not it's optimum for the cartridge (as they did in going from the 20" M16 rifle to the 14.5" M4 carbine).

Yeah. If 6x41 were available as factory ammo, I'd jump on it without hesitation. Hmm. It suddenly occurred to me that maybe the reason I never bought a 6.8 or 6.5 rifle is because subconsciously I realized neither one was what I really wanted...

Truth be known, if I had more time to reload, I would already own a 6 X 41.

[stanc]

I only see two problems with your statements here, Stan.

a. The deer have been shot with bullet types very unlikely to be used by the Army, which makes that part irrelevant to military use of 6.8 SPC.

Since caliber does not solve performance problems in itself, the military is finally realizing that bullet construction is much more important to lethality and the possibility of multiple modes of function. If I'm wrong, then why is there a move already afoot to field the OTM, the SOST / TOTM? If nothing else, these developments show that the same bullet types killing deer and hogs so effectively, are already getting both recognition and being issued as we speak. Perhaps not ubiquitously, but they are on the radar and in the plans for the future. IMO, the simplest thing they could do to improve performance is specifically to cease using non-expanding bullets. All-copper, or TOTM works better for multiple purposes than does a FMJ or penetrator type bullet.

The so-called "OTM" (i.e., Sierra MatchKing) has seen only limited use by the Army, which AFAIK has no plans to use the SOST. The latter is currently being employed by the USMC in Afghanistan, but who knows if (or how long) that'll continue? AFAIK, TOTM was only a developmental load. I'm also wondering if the 5.56 "brown tip" (TSX) round was just an experiment, since nothing more has been published about it since early 2008 and none seem to have shown up anywhere.

I've heard nothing about any of these being "on the radar and in the plans for the future." What's your source for this info?

b. SSA gel tests of an M855-type 6.8 load a few years ago showed results little better than 5.56 M855, according to Art Kalwas. Plus, there is no public data on gel tests conducted with M855A1-type bullets in 6.8 SPC, or if in fact, any were ever even built and tested. (All we have in regard to the ARDEC tests of alternate calibers are third-hand reports that .277 bullets did better than .257 and .243 projectiles, but I've seen no mention of either bullet weights or the cartridges used.)

If I were shooting anything, animal vegetable or otherwise, I would not preferentially choose a "M855 type bullet," in any caliber. Why waste time testing something that we already know sucks? If you put that bullet, eschewing better designs, in 5.56, 6.8 or 6.5 Grendel, then they all would be worse off. IMO, the best way to castrate / ruin the performance of any caliber or cartridge design, is to use the poor M855 design for anything. I have many thousands of hours in the field and thousands of AAR's on dead things and I can tell you that the M855 "penetrator" style bullet is the worst design of any I've used. I have shot car doors, gel, and animals and my results agree with most military testing. I must say, I also liked the performance of my 6MM Remington on many of the same things. The 6mm 85 TSX was awesome, and the Hornady Spire point in 6mm was also devastating. I sure hope nobody wants to put an FMJ or M855 type bullet in the 6 X 41. Please don't.....

Not me. But, the Army has shown no indication (of which I'm aware) of switching to expanding bullets. Until a year or so ago, the general issue round was M855. Now, it is M855A1. Both are penetrator rounds, with a steel tip ahead of a base slug, and held together by a copper jacket.

Therefore, I have to conclude that any alternative cartridge would -- at least as things stand now -- have to also use an M855A1-type bullet. So, I see no relevance in how well TSX, Accubond, or other hunting bullets perform.

c. Wound profile in gelatin is only one factor in selecting an optimum cartridge for military use. There are other things to be considered, such as trajectory, wind drift, danger space, and tracer performance, to name some. Even if 6.8 is the best choice for carbines, it might not be the best option for LMGs or DMRs.

Now, with this, I do agree. 6 X 41 does equal the bullet weight of the best 6.8 bullets (~95 grains) and much better BC. Therefore, if the velocity were equal (which it seems like it will be close) then the 6 X 41 could be well-suited to both SBR's, SMG's and alternatively, DMR with long barrels. The thing that remains to be seen is if it can reach 6.8 velocities in 8, 10, 12 or 14.5" barrels. Realistically, do you think we are likely to ever see the Army go with one cartridge for all its various squad rifles?

There are historical precedents for a single caliber.

In the '20s and '30s, the military had one cartridge (.30-06) for infantry rifles, sniper rifles, BARs, and machine guns.

In the late '50s and early '60s, they had one cartridge (7.62x51) for the M14 rifle, M14A1 automatic rifle, M21 sniper rifle, and M60 machine gun.

The reason they now use two different calibers is because the one (5.56x45) that was forced upon them by the SecDef in 1963 has proven inadequate for some purposes.

To answer your question, IMO it depends on whether or not a cartridge offers good enough performance to be used in place of 7.62x51 rifles and machine guns, yet is also viable for the short, lightweight carbines the Army desires as standard individual weapons.

[M995]

I found interesting is that although he says he isn't a proponent of any particular cartridge or caliber, on page 1 is a photo of 6.8 SPC, and in the ammo weight comparison on page 11 he also uses 6.8 SPC. (154 rounds lined up so nice and neat. If I tried to do that photo set-up, I'd likely never get them all to stay standing!)

I have talked to Mr. Schatz several times both on Hkpro forums and through email. He isn't trying to say a specific caliber is superior to the others and he has even stated that one should take the caliber studies of the past as a starting point (ie .280 British). He told me that he believed that something like a 6.5-7mm intermediate round with proper Blind to barriers ammo would give better performance than 5.56mm.

I think the reason Mr. Schatz mentioned 6.8mm SPC was b/c it seems to be the most developed intermediate round when it comes to military use (there is no AP ammo for 6.5 Grendel) and he is just trying to give an example of a superior COTS round but is not advocating that this is the most superior round.

Also, recently Cris Murray told me that he is planning on developing a 6.8x46mm cartridge. I think that both Mr. Murray's 7x46mm UIAC and his newer 6.8x46mm round should be considered if one was planning an intermediate caliber study to replace 5.56mm.

IMO, the Army should adopt a true BTB round and leave penetration of steel plates and armor to AP ammo like M995/M993.

[stanc]

I think the reason Mr. Schatz mentioned 6.8mm SPC was b/c it seems to be the most developed intermediate round when it comes to military use (there is no AP ammo for 6.5 Grendel)...

It used to be true that 6.8 SPC was more fully developed for military use, but with the recent change in bullet types being used by the Army and Marines, I now have to rate 6.8 and 6.5 as being equal in that regard. Neither cartridge has M855A1-type or SOST-type projectiles, and neither has tracer or blank ammo.

Although it's true that 6.5 Grendel AP is still in development, whereas 6.8 SPC AP is on the market, but IMO that is offset by the MatchKing loads. The 115gr 6.8 MatchKing has such a low BC that forum members protest whenever it's compared to the 123gr 6.5 SMK. So, 6.8 SPC needs an improved SMK, and 6.5 Grendel needs a good AP.

...and he is just trying to give an example of a superior COTS round but is not advocating that this is the most superior round.

I agree.

Also, recently Cris Murray told me that he is planning on developing a 6.8x46mm cartridge. I think that both Mr. Murray's 7x46mm UIAC and his newer 6.8x46mm round should be considered if one was planning an intermediate caliber study to replace 5.56mm.

Cris told me the same thing. I think Murray's 6.86x46 may have more potential than his 7x46. I look forward to learning how things go with 6.86x46 development.

IMO, the Army should adopt a true BTB round and leave penetration of steel plates and armor to AP ammo like M995/M993.

A number of people share that opinion. However, I think the Army wants a general-purpose bullet that will give acceptable performance in possible future wars, rather than optimizing the bullet for the current conflict.

[M995]

A number of people share that opinion. However, I think the Army wants a general-purpose bullet that will give acceptable performance in possible future wars, rather than optimizing the bullet for the current conflict.

I totally agree that the Army seems to want a do all projectile. But a do all projectile that does everything well is not possible. For eg. M855 and M855A1 are not blind to barriers and they can only defeat some Lv3 armors that are made of Dyneema (I am not sure if they still have 12" penetration after defeating Dyneema armor). M855 and M855A1 cannot defeat ESAPI style armor (which is the style of armor most modern armies wear), only M995 and M993 can do that.

Also, in terms of soft target performance M855A1 may not have 2" upset, which is ideal.

Regarding your comment about 6.8mm and 6.5mm being equally developed, I think 6.8mm SPC is still more developed b/c it has a BTB round (the 85 grain TSX), which is kind of similar to the 70 grain Brown Tip and I have not seen any BTB loads for 6.5mm Grendel.

Anyways you make very good points and I am also very excited about Mr. Murray's 6.8x46mm UIAC b/c I think it would be the better round for combat within 400 yards (which is where most rifle engagement take place) while still being adequate for long range use in MGs and SAWs.

[stanc]

Regarding your comment about 6.8mm and 6.5mm being equally developed, I think 6.8mm SPC is still more developed b/c it has a BTB round (the 85 grain TSX), which is kind of similar to the 70 grain Brown Tip and I have not seen any BTB loads for 6.5mm Grendel.

There is a 6.5 ("brown tip" equivalent) TSX load, too.

http://www.alexanderarms.com/item/12...ammunition.htm

[M995]

There is a 6.5 ("brown tip" equivalent) TSX load, too.

http://www.alexanderarms.com/item/12...ammunition.htm

Thanks for the info. My bad, I haven't been keeping track of 6.5G development. I guess we can say that 6.8mm SPC is more developed in for military assault rifle use (where ranges are within 400 yards) while 6.5G is more developed for DMR use.

Anyways, my comment about adopting both BTB and AP ammo (and not just relying on M855/M855A1 as the do all projectile) is also shared by professionals like Dr. Roberts and Jim Schatz. I do agree that M855 has it's uses like in increasing helmet penetration range when using the SAW.

[stanc]

Thanks for the info. My bad, I haven't been keeping track of 6.5G development. I guess we can say that 6.8mm SPC is more developed in for military assault rifle use...

"What do you mean 'we' are going to die, white man?" said Tonto to the Lone Ranger, as a marauding band of Indians were closing in on them.

Sorry, since there are no 6.8 loads of the types (M855A1, Mk318) currently used, I can't agree.

Anyways, my comment about adopting both BTB and AP ammo (and not just relying on M855/M855A1 as the do all projectile) is also shared by professionals like Dr. Roberts and Jim Schatz.

However, their opinion doesn't matter. It's what the decision makers in the Army opt for that counts.