I have two BCM rifles, a 16" midlength and 11.5" SBR, both with the govt material spec and "govt profile" (except for length) barrels.
I don't shoot them a lot, but the only quirks I've noticed are:
-During one range session with the 16", the CH was unlocking during firing; I could never figure out what was going on with that. I changed to a different CH and it hasn't happened since.
-The main action spring in the 11.5" (same lower as the 16") seemed to not be as strong as that in my unfired Colt 6920 once when I was comparing just the two. I've meant to compare, just by feel, to some others but haven't done that yet. The only reason I was comparing those two is that is what was in front of me at the time, and the 11.5" once didn't go into battery all the way when I was charging it from a full mag, using the CH (a situation of maximum drag on the BCG). It only has done that once and the rifle is still relatively new.
Overall I think they make good quality stuff, and their lowers also have every quality I like to see in a lower.