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
CVLIFE 7.62x54R Bore Sight Red Dot Boresighters
UNKNOWN 7.62X54R CHAMBER ADAPTER
30-30 chamber adapter i made from a steel case 7.62x54r : r/MosinNagant
TFB Review: The Shooters Box 577/450 Chamber AdapterThe Firearm Blog
CVLIFE 7.62x54R Bore Sight Red Dot Boresighters
Chaszel, Author at Chaszel
Auxiliary cartridges By any other name, still twice the fun - TheGunMag - The Official Gun Magazine of the Second Amendment FoundationTheGunMag – The Official Gun Magazine of the Second Amendment Foundation