Shotgun Adapters are also called a reducer sleeve, barrel insert bushing, chamber reducer, ammo adapter, and ammunition converter.
Shotgun Adapters instantly convert your shotgun to shoot smaller diameter ammo.
The History of Shotgun Adapters
A caliber conversion sleeve or adapter sleeve is a device which can be used to non-permanently alter a firearm to allow it to fire a different cartridge than the one it was originally designed to fire. The different cartridge must be smaller in some dimensions than the original design cartridge. Alternative names sometimes imply the type of dimensional difference. A chamber insert may be used for a shorter cartridge of similar base diameter. A supplemental chamber or cartridge adapter is typically used for a shorter cartridge of reduced diameter.