I have three BCM AR-15 uppers, each with a BCM BCG. Only had one problem with one of the BCG's and BCM fixed it. Turnaround was less than three weeks.
Uppers
rifle length gas system, 18" stainless barrel
http://www.bravocompanyusa.com/BCM-S...-missg2-15.htm
Midlength gas system 14.5" barrel w/Surefire brake permanent attach
http://www.bravocompanyusa.com/BCM-B...mid-14-bfh.htm
Carbine length 11.5" stainless barrel (as a pistol until politicians amend ridiculous laws about NFA items in Washington state)
http://www.bravocompanyusa.com/BCM-S...11%20ss410.htm
The BCG on the 18" was the one that went bad, but no problems as of late. the rifle will shoot 1-1.5 MOA with factory American Eagle 55gr M193 5.56. Haven't tried the heavier stuff for accuracy yet, but it should shoot fine with the 1:8 barrel. No hiccups, overgassing, or undergassing due to fit and finish on all rifles with the M16 carriers and standard weight buffers/springs in carbine and rifle length stocks.