Chiappa Resurrects the M6 Survival Gun w/ 10+ Caliber Options -The Firearm Blog
Gun Adapters
Gear Review: TRU-BORE 12 Gauge Chamber Adapter
Boland Production Supply, Inc.
12GA to 10MM Shotgun Adapter - Chamber Reducer - Stainless - Free Case & Ship !! | eBay
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