It is too soft and heavy recoil will peen it. It is inertia. One reason to not shoot heavy bullets.
I left part of the story out since I had assumed it was only coincidence, but now I'll go ahead an mention it.
As I said, I probably have put about 400 rounds through this revolver, mostly cast 240 grn bullets. I recently bought some 300 grn Sierra SPs and loaded up some of them. The cylinder locked up after I had fired the third 300 grainer.
???
