Miniature calibre (caliber) adapters and conversions
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
The 30:30 Barrel Adapter For 12 Gauge From Chaszel - YouTube
The Utility of 12-Gauge Caliber Adapters, The Good, Bad, & Ugly -The Firearm Blog
shotgun adapters from the shooter's box, let's try them out. shotgun adapters review. - YouTube