M855 v. M855A1 U.S.M.C. And U.S. Army Differ In Their Opinions.

Rep. Loretta Sanchez, D-Calif., is the ranking member of the Subcommittee on Tactical Air and Land Forces and she wants to know why the Marine Corps uses the M855 5.56mm round and the Army uses the M855A1.

Representative Sanchez comments:

“Maintaining two inventories of the same size combat ammunition is probably not the most efficient way to go,” Sanchez said.

“I just think it looks bad. It makes us all look bad. It appears very wasteful from the outside to have the Marines and the Army not buying the same bullet.”



The U.S.M.C. uses the M16A4 – it’s a 4th generation M16. The rifle is chambered in 5.56 x 45 mm (NATO) and has a barrel length of 20 inches. The U.S. Army has standardized on the M4 also chambered in 5.56 x 45 mm (NATO) but with a barrel length of 14.5 inches.  The 5.56 x 45 round, designated as M193, was designed with a 55grain projectile and intended for a 20 inch barrel.  M193 relies on a muzzle velocity of 3000+ feet per second to achieve its terminal effectiveness; however, it lacked penetration performance against hardened targets.

The M855, with its steel penetrator, effectively addressed that concern and when fired from a 20 inch barrel, like those used on the M16A4, the round has sufficient muzzle velocity to achieve the desired terminal effects even with its 62gr projectile weight. Subsequently, all the services adopted the M855.

With the emergence and adoption of the M4 by the U.S. Army the situation changed. The M4 with its shorter barrel did not posses sufficient muzzle velocity to achieve acceptable terminal ballistics and  the M4’s shorter barrel, even with its 1:7 rifling, did not provide the level of accuracy that the 20” M16A4 was able to deliver, so the U.S. Army called for an enhanced round, which was ultimately adopted by the Army in 2010 and designated the M855A1. This new round offered some interesting features. First, it was lead free, which I think was more of a political statement than anything else. However, the real reason for adopting the M855A1 was:

  1. Improved external ballistics, optimized for the M4 carbine. For example, higher muzzle velocity.
  2. Improved projectile geometry for better penetration and terminal effects.
  3. Reduced flash and smoke signatures from improved propellants.

Readers who have been following the M4 “lethality” concerns will recall that the U.S.M.C. was conspicuously absent for those discussions. Their choice of rifle was the principal reason for that absence. The U.S.M.C. was simply not experiencing a performance issue with the M16A4 and M855 combination.

The M855A1 has, from all reports, addressed the overwhelming majority of issues with the M4, but does it perform equally well when used with the M16A4? This is a question that needs to be empirically answered. Ammunition IS NOT weapon system agnostic as most experienced shooters already know.

Suggested Approach:

So, perhaps the best approach is to ask the U.S.M.C. to conduct comparative tests, with both M855 and M855A1 ammunition types, and present its findings to the Subcommittee on Tactical Air and Land Forces along with its supporting data so the appropriate decision can be made.

This entry was posted in Ammunition and tagged , , , , , , . Bookmark the permalink.

1 Response to M855 v. M855A1 U.S.M.C. And U.S. Army Differ In Their Opinions.

  1. Pingback: The Future of Soldier’s Ammunition – Mike Lima Consulting

Comments are closed.