NAA Mini Revolver Exploded View

Colt open-top .22 of 1872.  The .22 short round was developed for the first model Smith & Wesson.  Years passed before other companies could compete, since Smith & Wesson held the patent on the process for drilling cylinders from end to end so they could accept cartridges.  The Rollin White patent expired in 1869 and the Colt gun above appeared three years later.