Enhanced 5.56mm Round?

UrbanSurvivalSkills received an e-mail from Hank asking if we had any information on the military replacing the M855 5.56x45mm standard issue round? Hank said he did not know what the name (designation) would be but had heard that this new round was much more powerful and accurate than the older cartridge currently in service.

UrbanMan Replies: Okay Hank, I pinged several old friends of mine and this is what they tell me:

There is a new round and it is called the M855 Enhanced Performance Round (EPR). I had not previously heard about it and my sources have not seen it, have not shot it, nor been issued it, but have heard about it.

Apparently it is a hotter round, well over 3,000 feet per second muzzle velocity, which also means the chamber pressures will be greater and the barrels will burn out faster. And just because a round is faster, it does not mean it is more accurate - in fact, when pushing the velocity issue and increasing chamber pressures, usually the accuracy suffers.

The accuracy claim may simply be a (surmised) enhanced hit probability at the longest ranges due to the higher velocity. But again, more than velocity factors in accuracy,....bullet weight, bullet design, rifling and rate of twist in the barrel, and several more factors are involved.

This new EPR round is supposed to be able to penetrate 3/8ths inch of steel at 400 meters. I am told that Special Operations will not be using this new round, but continues to use the old M855 62 grain (SS109) and a newer round called the SOST (for Special Operations Science and Technology) or sometimes called the OTMRP (for Open Tip Match Rear Penetrator) and goes by the Navy designation Mk318 MOD 0.

These new 5.56mm rounds are all designed and built at least partially due to widely believed and reported poor performance of M855 62 grain in soft tissue. Soldiers and Marines shooting skinnies with the M855 62 grain round would often experience over penetration meaning alot of the buller energy was leaving the target. Sometimes this is called an ice pick type of wound.  And as you'll remember, stopping power is based somewhat on how much energy of the bullet strike stays in the target.

Rather than going to a different caliber, such as the excellent 6.8mm SPC, the military decided to minimze costs of re-barelling, new magazines, etc. and attempted to make a better round given the parameters of the 5.56 x 45mm cartridge.

For my 5.56mm (.223) guns, I'm happy with the variation of ammunition I have available for them.  There are things more important than the bullet configuration or weight such as a person's ability with the firearm.