The only negative feed back I have heard, is if you have failure such as a primer coming out of the case, ( which should not happen, but does ) it will fall into the trigger group and lock it up, and it is not a quick fix, where the factory type set ups, even if they are the high quality adjustables, like Geislle, accuracy speaks, JP, Jard, allow you to pull the rear pin, pivot the upper and more than likely, turn it upside down, shake it, primer falls out and your back in biz.