Manufactured in 1864. The serial number is stamped on the underside of the barrel and on the left side of the grip strap as well as written in pencil on the inside of both grips. The partial serial number "04/21" is stamped on the rear face of the cylinder. All of the serial numbers match. A two initial, script, Ordnance final inspection mark is stamped on the lower edge of the left grip. Single letter Ordnance sub-inspection marks are stamped on most components. As the primary handgun issued to Federal cavalry regiments during the last two years of the Civil War, these rugged revolvers remained in service with the regular cavalry regiments on the frontier until they were replaced with the Model 1873 Colt Cavalry Revolvers in 1875.