The .22 conversion is almost as old as the autopistol itself. Shortly after the adoption of the 1911, Springfield Armory began experimenting with ways to train soldiers more cheaply and without the blast and recoil of a full-power pistol cartridge.

Early attempts ranged from a simple barrel with an offset bore that would align the rimfire cartridge properly with the firing pin, as well as an armory-made adapter with an internal bolt, before finally arriving at the Colt Ace, a blowback conversion with a full profile, hollowed-out slide that mimicked every aspect of shooting the big bore except for the recoil. Added recoil would come with the later Service Model Ace and its floating chamber, a recoil-amplifying feature dreamed up by moonshiner David “Carbine” Williams while he lay shackled at night in a prison camp in the North Carolina woods doing hard time for murder.

READ MORE: There’s A Lot Going On… Inside the .22 Conversion – American Handgunner