marines are now using PMAGs

[Disposable Heart]

The USMC is transitioning to the same ammunition the US Army is using. Ammunition: Congress Demands Army and Marine Corps Standardize Rounds - The Firearm Blog

From someone that seems to know what's going on:



So, apparently, the USGI mag the USMC is using has compatibility issues with the incoming ammunition.

Bingo. Only the Magpuls and the tan follower mags are approved for M855A1, which is tearing up feedramps with green follower mags.

Since Magpuls are approved by some units in the .mil, it only makes sense.

Remember, the military thinks magazines are disposable items (as well as Matech sights, believe it or not!). Poly would likely be cheaper if done on a mass scale (such as Magpul's manufacturing base), can feed M855A1 and the poly mags won't wear out lowers with insertion over time, it's a win-win.

 

[STEEL CORE]

OK so you are really old if you were in the US Army and used the Canadian THERMOLD black mags, back in the day.

 

[Excalibur]

Bingo. Only the Magpuls and the tan follower mags are approved for M855A1, which is tearing up feedramps with green follower mags.
.

What is so different with the M855A1 round that makes it tear up feed ramps?