Those rifle loads weren't that hot. I suspect a bum reload took the S&W apart.
I just noticed that the OP said the barrel marking read "32/20 US Service CTGS". Needless to say, the .32-20 was never a U.S. service cartridge. The Spanish apparently copied part of the marking from an S&W marked for ".38 Special and U.S. Service Ctg."
Jim
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