While soldiers are typically lauding the M855A1 Enhanced Performance Round, it has come at a cost of long-term durability and reliability of the M4A1. The M855A1 exposed steep tip loading is substantially different from its predecessor, the venerable M855 steel-core, which had been in-service for decades prior to the change-over. The high-pressure load to eek out velocity has been burning through barrels quickly and another issue reared its head from the steel tips gouging the upper receiver’s extended aluminum feed ramps over time.
To “solve” the problem, the US Army developed a “new” magazine, dubbed the Enhanced Performance Magazine. Outside of some minor changes on coatings and colors, the major change has been around the feed lips, which are bent to present the round higher and feed the tip of the round into the steel portion of the barrel extension.
The “enhanced performance magazine” brings the M4A1 feed ramps full-circle. Originally developed to assist with feeding rounds in the faster-cycling weapon, the extended aluminum ramps from the extension are now a liability as the steel tip of the enhanced performance round gouges the softer material. Given this change, I would not be surprised to see the “M16” feed ramps make a comeback to likewise combat the issue once all the old magazines are out of the inventory.
Soldier Systems has details on the new NSN’s and the phase-out plan for Big Army. Check their coverage out here.