Gun Runner: Some Argentine Mausers were made in the 7.65x53 caliber, but I suspect those were the Argentine Mausers made to Argentine specifications. You may have an earlier one imported to Argentina that was in the original 7x57mm caliber. If you have fired a 7x57mm cartridge through the rifle without any case deforming, you probably have one of the earlier ones.
Hate to say this friend but you still may wish to make the trip to your gunsmith to have the rifle checked for headspace and parts inspection - if she is still good, then you should be able to shoot standard 7x57mm ammo through it. Sorry to read it has been Bubba-tized, but even in the 7x57, a Bubba-tized Mauser can make a good truck or back yard or camp gun. Since Bubba got his hands on it, the value of the original may have gone down but it's functional value may remain. HTH. Mikey.