No, the gas guns typically start to eject rounds "early" so brass stretches more. Also there isn't the handle mechanical advantage of a bolt to close/chamber a round that is long( no headspace or bolt face clearance). I like 0.003-0.004 bolt face(headspace) clearance in the winter, so all rounds will go into battery without forward assist. Full length size all AR rounds, I check brass and finished rounds with an ammo checker. Accuracy varies, due to shooter ability/technique and quality of the barrel and trigger as well as the ammo used.