Reliability and Durability Issues with the M855A1 Round


Reliability and Durability Issues with the M855A1 Round

Oh the rivalry between the Army and the Marine Corps. Now apparently the Army is trying to bring down the Corps with the introduction of Project Eldest Son v2. I’m kidding of course. But the new M855A1 round is causing problems.

If you recall a few months back during appropriations for the 2017 NDAA, concern was expressed over the issue that the Army and Marines field two different variants of 5.56 mm ammunition. If there is not sufficient reason (basically an “emergency”) for the difference, then they have to start using the same round within a year after the bill is passed. Really it does make sense from a logistics standpoint. All of our forces should be running compatible equipment and expendables.

The new M855A1 “Enhanced Performance Round” has a steel penetrator on top of a solid copper slug. The issue is actually only with the M27, which is the replacement for the M249, and which may become the replacement for the service rifle for infantry battalions.

The reliability problem that they are seeing appears to be related to the magazine and how it was feeding into the weapon. And big surprise here, the Magpul PMAG is actually the solution. In fact Marine Corps System Command authorized the use of PMAGs for the M27, M4, and M16A4 since it is possible to encounter the M855A1 downrange. As of now the root cause has not been determined–just that the PMAG is the current solution.

There are also some durability concerns since the M855A1 is a hotter round. The fear is that it is going to cause earlier bolt-part failures and barrel failures.

You can read more about it here:

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Tom is a former Navy Corpsman that spent some time bumbling around the deserts of Iraq with a Marine Recon unit, kicking in tent flaps and harassing sheep. Before that, he was a paramedic somewhere in DFW, also doing some Executive Protection work between shifts. Now that those exciting days are behind him, he has embraced his inner “Warrior Hippie,” and assaults 14er in his sandals, and engages in rucking adventure challenges while consuming copious water. To fund these adventures, he writes all manner of content (having also held editor positions at several publications) and teaches wilderness medicine and off-road skills. He hopes that his posts will help you find the gear that will survive whatever you can throw at it (and the training to use it). Learn from his mistakes--he is known (in certain circles) for his curse...ahem, find the breaking point of anything. You can follow him at

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