My cousin has a Charles Daly 7mm Rem Mag (Mauser Action). He was firing factory Winchester 150 grain loads (grey box). He noticed two fired cartridges had developed cracks in the case body. I'm not sure what caused this and my cousin lives some distance away so I'm just going on what he told me. Could it be defective factory ammo? or maybe oversized chamber? I suggested that he measure his fired and unfired cartridges with a micrometer, and to clean and inspect the chamber to see if that can shed any light on the problem. Does anyone have any ideas before going to a gunsmith. We had shot the rifle previously (it was brand new) without any issues. The round count is probably less than 150 rounds.

Thanks
Ed

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