233

  1. D

    Gunsmithing .233 ammunition versus 5.56 pressure problems

    I built a couple of AR-15 uppers for some clients and when test firing each upper I could not get the bolt to latch back on the last shot. After changing gas blocks, BCGs, etc, I finally tried some 5.56 ammo and it worked fine. The ammo I was originally using was .223 PPU 69grn. Has anyone...