Manufactured in 1874 and within a serial range of known nickel plated Ainsworth inspected revolvers. Four basic theories for the existence of this highly controversial grouping of nickel plated U.S. Cavalry revolvers have developed over the decades and are the following: 1) issued to Indian Scouts and Police; 2) special order "officers" revolvers; 3) surplus State of Virginia Militia revolvers sold to and nickel plated by Colt or commercial retailers; and 4) U.S. Navy revolvers. See Kopec's "A Study of Colt Single Action Army Revolver" for the history related to this ongoing debate. Orville W. Ainsworth's small "A" sub-inspection mark appears on the barrel, trigger guard and back strap. "U.S" is stamped on the left side of the frame near the two-block patent dates marking. A "P" proof mark appears on the barrel and cylinder. Matching serial numbers are stamped on the frame, barrel and cylinder. Both grip straps have the serial number "12923," possibly a factory error.