So I built a mega maten large frame ar in 308 and bought some 20rd Hexmags. Went to the range to tune the gas block and loaded single rounds into the mag until I got the bolt carrier to lock back... but it wouldn't. Up looking into the issue, the follower of the magazine was being pushed down by the bolt when I manually lock the carrier to the rear. So when I fire and it's operating at full speed the follower is being pushed down by the bolt and dropping the bolt catch and the carrier just moves on forward and closes. Anybody else ever notice this? I'm buying Pmags and steel sr25 type mags later today to try if they work.