Could the use of 'adapters' which fit into the chamber and swapping of the bolt, extractor and other parts allow firearms to use different calibers as long as the new cartridge is
Chaszel, Author at Chaszel
Review: 7.62x54R/.32cal Chamber Adapter - YouTube
TIL I can buy adaptors so my shotguns can shoot a whole bunch of other calibers just for kicks. : r/Firearms