While shooting a Barrett AR15 piston driven rifle suppressed we noticed heavy carbon on the brass and the shoulder has an odd stretch ring on it. Mostly factory but we did have some reloads in the batch. We also noticed the dirtier the rifle got the flatter the primers were. After about 400+ rounds the primers started popping out. I was told by a gunsmith a possible secondary carbon burn in the suppressor may be the cause. Any ideas?
