I experienced this with Remington brass in my 7mm-08, particularly with factory Remington loads I had, and was using to fire form. Interesting in that I did not see this with Winchester brass to the same degree. The issue all but disappeared in the win brass when I switched over to Lee Collet dies. It is less apparent in my loads with Varget and H4350, but still shows up with R15 loads. After 1 reload (!), the Remington brass felt like very loose primer pockets, so I discarded them.Anyone ever get it? And what causes it? I’ve been getting decent build up on some cases but not all. Tried multiple primers and same thing. It’s happening on a 7 Saum with ADG brass and reloader 26.
I wouldn't rule that out, but given the fact Stiller bolts are nitrided, i guess I may be upset if mine got coated.It looks to me, as was stated earlier, that it is probably coming from the bolt face. If the case wasnt sealing there would be soot all the way from the top down. When a primer is pushed hard enough to leak, it's been painfully obvious that it came from the primer. What you have almost looks like copper solvent on the bolt face. That stuff discolors brass and makes it look like that when it gets on it. Or possibly as others said some of the finish got on there?
I have never used that powder but some powders burn cleaner than others. I usually get powder residue on the case mouth with necked cases because of where they seal when fired. If powder residue is getting clear back to the bolt face either the case is not sealing in the chamber due to low pressure or the primer pocket is leaking. The primer should have stiff resistance when seating. I use varget and the new copper removing powders. I also find the cases come out cleaner and my loads more accurate when I load near max. When working up a load I approach max at 1/2 grain incrimints till the primer showes signs of flattening or max accuracy opens up. If primer starts to flatten first I back of 1/2 to 1 grain. If this only happens on 1 or 2 cases check for hair line cracks in the case body.Anyone ever get it? And what causes it? I’ve been getting decent build up on some cases but not all. Tried multiple primers and same thing. It’s happening on a 7 Saum with ADG brass and reloader 26.