primer cratering

  1. J

    5.56 AR15 (Slight primer cratering regardless of vel./psi)

    I have been getting slight primer cratering (CCI #41 primers), ejector marks/swipes, and an indented ring just inside the rim of the casing using one lower (M&P15) as well as ejector marks/swipes with a second lower (80 percent) with both my uppers (18" B.A. Barreled upper/ 20" WOA SPR barreled...