What Caused These Marks On Brass?

[Precision Underground]

Bought some once fired hornady brass to load bulk match-ish ammo for a large frame. I’ve never seen rings on brass like this- it’s a perfectly circular indentation around the rim of the case. What the heck did this and does it matter? I haven’t dug through all of them but I’d guess it’s on 30-40% of them. It was supposedly bolt gun brass and looks clean enough to be.

 

[Precision Underground]

Checked to see if primer pockets are loose and they aren’t.

 

[moaorbust]

Huh. That looks like a mark from too high pressure. Never seen a ring though. Usually just extractor marks.

 

[b6graham]

what does the bolt look like?

those are odd though

 

[DIBBS]

Those rings are a result of the manufacturing process. I have seen it on a number of factory Hornady ammo in both 6 & 6.5 Creedmoor.
I have reloaded some of these cases myself and it doesn't seem to affect accuracy which surprised me.

 

[Precision Underground]

Thanks guys. Yea I was surprised to see something I’ve never seen before. My first thought was pressure too but you’d think there’d have to be ejector marks unless the bolt had some kind of raised ring on it. @DIBBS answer is what I was hoping for.

 

[DIBBS]

Factory 143 ELD-X

 

[Precision Underground]

Factory 143 ELD-X

View attachment 8128435View attachment 8128436

Thank you sir. Glad I don’t need to sort or cull any of them!