Case rim separation?

[Helidriver]

I'm at a loss as to the cause of this and I'm shocked I didn't notice it while I was loading up these rounds. I was shooting today and while I was checking for signs of pressure I noticed these rings around the case head. Every round in a lot of 100 looks like the one in the pic. My first thought was that they were scratches from the from the bolt face. I stopped shooting and when I got home I cycled a fresh case through the gun several times with no signs of this. It almost looks like the case rim is starting to separate. I've never heard of this. This was the 4th reloading of these cases. Any ideas? Has anyone seen this before?

 

[buffybuster]

What does your breechface look like?

 

[mdmp5]

There’s no way the rim would come off. It’s a solid piece connected to the head. That’s an imprint from the bolt face

 

[Helidriver]

The boltface has no corresponding markings on it. The gun is a Desert Tech and it is a little hard on brass but I've never seen this before. After some thought I agree, the web of the case is solid and these marks are well below where the solid part of the case head begins. I think I'm going to go ahead and shoot these. I have no signs of pressure with the exception of some mild primer cratering that I attribute more to the firing pin hole on the Desert Tech and not over pressure.

 

[Xander3Zero]

If you have any fresh brass, just try loading some up and see if the mark appears during fireforming.

 

[RTH1800]

Like to see an unfired case from that lot. BTW, what is that mark on the primer? Debris on the seating surface?

 

[Deleted member 10043]

That is a B

 

[mdmp5]

Like to see an unfired case from that lot. BTW, what is that mark on the primer? Debris on the seating surface?

B for bench rest. Think it’s cci

 

[SageRatSafaris]

Looks like a headstamp artifact, not a crack. “Every round in a lot of 100” reinforces that thought. I’d use them.

What is the “B” on the primer?

 

[SageRatSafaris]

Never mind the B question, I see the answer above.

 

[RTH1800]

I think the artifact is very likely.
Never seen that on a primer before. Guess I stocked up prior to that being done.

 

[BigTex]

it'll iron out if you load them hot enough.