Took my wifes ar 15 out yesterday to sight it in. First time out with it. It is a stock F1 bought from a store as new. I noticed abnormalities at case neck from spent brass from it. Looks to me like a chambering issue or head space off. Its chambered in 5.56 × 45. I was useing factory 55g 223 and some handloaded 55gr 223 with same issue. Here is picture of issue. Its the ones on end. Middle was out of another ar. Any ideas? It shot fine, just dont like what i see on brass.
