My chamber cast.is Cerrosafe, My casting is to poor to get a good read, however if I measure down the cast form base to shoulder I can not get small enough to record.427. This would lead me to believe that the case is .468/473? I believe the orig. cart.are rimed as the extractor is just like the extractors for the shot barrels is this a safe deduction? I found a proof mark of N 15gr. Does this help? Thank you for putting up with me! Peter