Thread: Split shoulders

There's more than one issue here.. hard to tell if those marks in the sidewalls are the start of case head separation or marks from the chamber or dies.. the damage on the rims look like extractor gouging from sticky cases or from the shell holder from stuck cases due to lack of propper lube in the dies.
Check the inside of case where that ring is for a groove..
Hard brittle cases or over work hardend/sized will case all this especially if they are sized outside of a few thou head space tolerance