Had a friend bring his DPMS AR to the range today to zero. The rifle fired fine with the gas impingment system however he swapped in a free float rail and an Osprey piston. When fired, the empty casing is ejected however it's not cycling the next round. Tried several different mags and even put a colt bolt in the carrier and no change. My only thought is that there's too much gas escaping from the piston. The buffer and spring seem fine also.
Any thoughts?
Any thoughts?