Military inspection ted conversion of a Model 1851 36 caliber Navy revolver serial number 28782 manufactured in 1853. converted to 38 caliber. Conversions are the transition from percussion revolvers to center fire Colt Single Action Army revolvers. Starting in about 1868 colt knew how to make cartridge weapons but had not yet designed or manufactured its iconic 6 shooter the single action army first issued in 1873. Colt used that period to convert its percussion revolvers to cartridge., such as this example. Mechanically fine