Originally Posted by
mark5pt56
Other than the stuff listed, try pulling the bolt catch and checking for anything inside or a weak spring. I had an odd one the other day, the detent got stuck in the depressed position. Also check for correct lock up with the pmags. Put pressure on them, mainly to the rear, possible the followers may be worn at the contact point and not engaging the BC. I've found some of them to have a slightly shorter follower, coupled with that and if the catch area is worn, it may cause issues.