I was getting a few every 50 or so from my ar15. I looked at the firing pin and replaced it. No more piercings after 50 down the pipe. Will continue to monitor. Im thinking either the firing pin got damaged from a piece of brass sticking to the tip or some cheap factory plinkers are to blame. My load wasn't hot or anything and it was 70ish degrees outside. (Mixed headstamp, wsr primer, 55gr vmax, 25.8 gr wc748, 2.250 coal) What do you think? Ive also switched to rem 7 1/2 primers as ive read they are harder.