The model 1849-U was designed for the smaller Uberti .31 caliber 1849 model revolver to fill the need for a modern pocket pistol for CAS Matches. The RD1849U is unique in that, not only does it convert the small pocket model 1849 to fire the 32 S&W cartridge, it also converts it from a five shot to a SIX-SHOT revolver! (If, after installation, you are unsure of the fit, please take your revolver to a competent gunsmith or contact R & D Gun Shop to make sure you have the cylinder installed correctly.)