Marks on brass - safety issue?

[JSH]

What does the chamber look like?

A chip doesn’t usually leave that good of a profile. Stranger things have happened.

 

[47WillysGuy]

I noticed some marks on fired brass from a 6mm Creedmoor that have me concerned and confused as to what caused them. The loads were from an OCW test I was doing and this is just the second time fired for the brass. The marks did not appear on every case or every charge. The marks are definitely not from the chamber. I use a bore scope to look at the entire chamber and there are no machining marks that could make the marks on the brass. Also, the marks do not occur in the same place or the same type of marks on the brass. The marks are definitely a physical mark on the brass (won't just rub off) but I also can't really feel any kind of groove or ridge.

I am getting ready to send the brass back to the manufacturer (not named on purpose, but brass is quality and many top shooters use this brand). Should I hold on to the "evidence" or go ahead and send them back to see if there is some sort of manufacturing defect that is leading to the markings? I am concerned about safety of continued use. The manufacturer has offered to replace any cartridges.

Thanks for your thoughts, insight, and suggestions.View attachment 1147290

I'd brass polish or 0000 steel wool the marks to see if they can be removed. If an abrasive won't remove the marks, then cut one case in half with a dremel and visually verify case wall is not separating. And if you still have concerns about those cases, then I'd send all cases back to the manufacturer for replacement.

 

[Gina1]

Question... This picture you have posted, did you run your brass through an ultra sonic cleaner and then take the picture ?

 

[MNbogboy]

Knowing what incipient head separation rings have looked like in the past as a shiny ring at the forward part of the pressure cup, usually approx. 1/4" or so from the back of the case.
Visual inspection is part of each reloading routine.
These do not seem to fit that description. And your "paper clip" test probably verify that.
I have been stumped with rings similar to yours on several occasions. Turned out to be some sort of stain (or lack of stain) from using/leaving the plastic factory cartridge strips that are often used in packaging factory ammo. I use them on the range sometimes, in the field hunting and often between reloading process.
When I first saw these odd rings out comes the paper clip test (have a dedicated tool for this made with a re-formed tip on a screwdriver). Negative test....took a long time to figure it out and no they did not wipe off. 0000 steel wool gone!
Just something similar to the ammo box marks that other mentioned. But these seem to be caused by the plastic itself without vibration. Could be from case lube when confined... not sure.
Just a thought because of the random height.

 

[jds holler]

This situation is obviously a segmentation, in the creation of the amalgamation. jd

 

[grovey]

This situation is obviously a segmentation, in the creation of the amalgamation. jd

I concur.