Brass - Line; Head separation??

[257WHBY13]

Once fired 8mm Rem Mag brass, Nosler, Is the line beginning of head separation? The brass had the line before I reloaded & fired.

Thanks for your help!

 

[yobuck]

Take a paper clip and straighten it.
Then bend a small 90 degree turn on one end.
Use that to go inside the case and feel for a crack on the inside.

 

[biednick]

To me that looks like it's just a difference in the surface finish. There's usually a ridge on the outside if the case is thinning. A paperclip as mentioned is the best way to check if you're unsure.

 

[JKB57]

Looks a bit high for case seperation which is usually closer to the belt than yours,looks like storage marks or something similar,but as others have mentioned take a dental pick or paper clip and run it up and down the inside of the case wall and see if you feel an indentation in that area,if the brass had that line before firing I would say its just something in the manufacturing process.