Bullet Marring in Grendel AR

[DL42]

I just loaded two more dummy rounds as a test. No gouges whatsoever. That is another reason I tested factory ammo along with my test loads. I do believe that the marks are occurring while the round is being chambered. I also tried resting the load on top of an empty chamber and chambering it that way, with the same results. I just find it so odd that the rounds did not come out like this when I built the upper.