5.56x45 Low Profile Mid-Length Piston Upper with Aero Precision 15" M-Lok Rail

Bottom line upfront: this piston driven AR upper is a superbly well built, easy to use, very accurate, super easy to maintain, and backed by excellent customer service. I recently purchased the 5.56x45 Low Profile Mid Length Piston Upper with 15" Aero Precision M-Lok Rail and added a Aero Precision lower to complete my rifle. Upon firing it for the first time I encountered issues with it locking back on an empty magazine and sporadic failure to feed. I contacted Black Rifle Arms (BRA) about the issues and BRA immediately responded to my emails with emails and personal phone calls. After trying the trouble shooting recommendations, it was determined that there was an unknown issue with the gas system. BRA paid to return the upper, corrected the issue, and returned it back to me at no cost. The rifle now runs like a dream and functions flawlessly. At 25 meters 3 round groups, the rounds consistently touching each other (wish I had more room in my property to shoot longer distances). I have put nearly 500 rounds through the rifle since purchasing it and have cleaned it once. Not because it needed it but because I though it was about time. The bolt, bolt carrier, and chamber almost looked like they have not been fired at all. All of this is firing Federal 55 grain and Federal 62 grain SP and Green tip ammunition. The one down side to piston driven ARs is that they are a hair heavier than standard ARs. Not an issue for me. I am planning on purchasing one of their piston driven 300 Blackout uppers as soon as I can sneak it past the wife. As a Former US Army Airborne Ranger Infantry Officer, I highly recommend this upper and any other BRA products.