I only have 570 rounds through my BCM 14.5" mid-length upper so far, 150 of those rounds were fired with my surefire suppressor attached, and I haven't had a single issue.
Ammo used was 370 rounds of Hornady 55gr Training ammo, and 200 rounds of PMC 55gr.
Thing is, I just now went and checked to see what weight buffer I had in there because I couldn't remember right off hand, and this ENTIRE time I've been using an H2 buffer by mistake. I thought it was a carbine or H1 this whole time:p Guess I'll just go ahead and keep it in there for now.
Anyhow, this upper is one smooth shooting bitch, that's for sure.

