Fail-to-feed problems FREQUENTLY trace back to a magazine lip issue. Try a different mag, or JUDICIOUS bending of the feed lips. Of course, round nosed FMJ ammo. Fail to fire is a sign that the round is not fully seating, and bolt is still a smidge out of battery- so firing pin energy is diverted to getting the bolt to close all the way. Diagnosis at long range is pretty hard, but odds are that's your problem.