552 Speedmaster issue

[rzwieg]

A friend has a 552 that tears the rim off the case and the report is unusually loud. It's cleaned well.
 
Does anyone have any ideas as to what the problem is?

[oneoldsap]

                  Check the chamber for rust or pittting .

[OLDHandgunner]

                  Check the chamber for rust or pittting .

Agree with above. I'd check the chamber again. Maybe a small burr.

[Frank46]

Check the ammo as well. I had some old maybe 20 years CCI ammo. When fired sometimes it would go pop and others would go bang. Noticeable difference in reports and failures to eject. This was fired in a marlin model 60 semi auto. Frank

[gunnut69]

Just another note and not to be flip..check the bore.. A few years ago a friend had a single shot rifle the started bursting cases and making more noise than normal when fired. he brought it over and I removed 12-15 bullets stuck in the bore.. after that I'd check for a dinged chamber under the case rim where the firing pin strikes. a bad dign will sometimes cause a burst case.