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US small arms terminal ballistics-failures and sucesses

The jury is still out on the US Army's M855A1 EPR round - it seems to generate significantly higher pressures. The USMC seem happy with their MK318 Mod 0. However, it is unlikely that either of these would be adopted by most European NATO members, because they lack jackets which entirely cover the tip of the bullet, as specified in the Hague Convention.
 
Higher pressure due to the lower compliance of the M855A1 cores vs the M855 lead slug?
As I understand it, it's optimized for M4 length barrels unlike its predecessor, maybe that's part of the reason for the hgher pressures?

I agree lots of european countries will be formally restricted by the 113 year old rules of a gentlemans war.
My guess is the wording in declaration III was aimed more at soft cores not being completely covered by the jacket than hard cores peering out as in the M855A1.
But I guess that apart from the SOST rounds you mention, most military ball rounds since 1899 rely on other mechanisms than expansion for enhancing wounding potential anyway. And I doubt european legal review boards would let the M855A1 through with this reasoning.

Any ideas on how it was made yaw independent as is stated in my second link?
 
bs-40 said:
Any ideas on how it was made yaw independent as is stated in my second link?
Click to expand...
I'm not sure, but I suspect that the exposed steel penetrator (which is not a very tight fit - reportedly it can sometimes be made to rotate relative to the rest of the bullet) breaks away easily on impact, causing more reliable fragmentation and a bigger wound channel. This of course would be another reason for Europeans to be unhappy with the bullet.

The higher pressures may in part be due to the fact that the EPR bullet, being lead-free, is significantly longer than the M855 and therefore penetrates deeper into the case, reducing the propellant capacity.
 
I believe it is a lot harder to design a well balanced general purpose round than a round mainly intended for one purpose.
SOST rounds may perform well on soft, unprotected targets behind light intermediate obstacles, my guess is the M855A1 aims for a broader military target set.
 
If I recall some of it had to do with the army wanting moe "Green" ammo, no lead etc. Plus a couple other reasons. But having shot a lot of the old and newer rounds I had a lot of trouble keeping a tight target group with the newer 5.56 and and they did not penerate into a number of different targets. example I shot .223 (5.56) for varmit shooting coyete, ground hog etc. But the new round is heavier so I can use it for deer now. Not admitting that I shot a buck with a 55gr .223 (that's against the law) but lets just say I did and I also shot a nice buck witht he new round - no comparison in peneration and clean kill the 55 gr was better.

Now if I do back to the war years (Vietnam) my targets there fell just as good as they did with a 7.62 round from the M60. Everyone bitchs about the too light no good M-16 5.56 round. to me it was just a matter of marksmanship and impact point selection. Not to say I didn't fire more rounds then I should have trying to hit my target (poor shooting discipline on my part).

Yes the 5.56 need to get heavier 62 or 63 grain, but it also needs to stay with the lead and steel.
 
I totally agree with you Mike. There was nothing wrong with the 55gr. round thru a 1 and 12 inch twist barrel ie., the M16A1.
 
I guess the heavier bullets are primarily needed to satisfy long range and intermediate target requirements (62 gr SS109 came out of the NATO helmet penetration requirement)
 
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