I separately purchased two Big Gunner 6.5 Creedmoor barrels last year -- one 16" and one 20" -- from two different vendors that I used for builds for myself and my father (his first AR type rifle). When Dad finally got around to shooting his a couple weeks ago he noticed unusual burnishing and striation marks on the brass (see pic). He also mic'd the spent brass and suspects the chamber is slightly egg shaped. After looking at his brass I pulled the box of 6.5 Creedmoor that I had and examined the very few pieces of brass that I shot from my rifle several months ago (life has gotten in the way of finding range time I'm afraid) and noticed similar burnishing marks though not as bad as the brass fired from his 16" barrel.
That said -- having shot in High Power competition for twenty years I've run many tens of thousands of rounds of .223 through various Krieger, Pac-Nor, and Wilson barrels over the years but I have to admit I've never seen markings like these. So my question is -- is this considered normal?