the wear I see on the BCG is not abnormal.Yes I absolutely did, I have had two other bcg's in this upper do the same thing. My original thought was close tolerances in this upper receiver, making all bcg's hang in this upper. This is the original BCG I bought for this receiver, so it's the one that has had the most time and rounds through it for this rifle. the other carriers have been put back in their perspective rifles and kept that way.
Putting other bcg's in this upper was a trouble shooting point. since I can't see obvious wear points on the receiver, but I can on the bcg, it seems to be a natural place to 'tweak' - but I'm looking forward opinions.
did you try the suspect BCG in a known good upper?
Probably unnecessary, as I am 95% sure the upper receiver is the problem.
I always leave 5% to blame on unicorn farts.