My ar15, ok its not a m16 but it is mil-spec except for the trigger group! anyways....I was at the range shooting some bulk ammo. Ripping open boxes loading and bumpfiring, double tapping, and rapid firing my little heart out when I load a fresh mag, slap the bolt carrier and the bolt stops and doesnt turn, I slapped the mag and racked the action.....nothin same problem. I took out the mag, cleared the chamber and locked the bolt back. Inspected and NOTHING. hmmm Again same problem when I ATTEMPTED to fire again. I took it out and used a dental pik made out of plastic to check the barrel extention. out pops a thin, peice of cardboardy paper from the box of ammo. no more than 3/8"x1/4" WOW Man it doesnt take much for these things to fail. I would be SOL if that was a mag loaded for home defence, witht hat peice wedged in between 2 cartridges. Sheesh