Offered is a historically significant nickel plated U.S. Colt Cavalry Model Single Action Revolver as it has taken center stage to a grand debate among Colt and U.S. military firearms collectors that continues on to today. Four basic theories for the existence of highly controversial nickel plated U.S. Cavalry Model 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. This example, no. 137603, is documented by serial number in Kopec's aforementioned ground breaking study on pages 237 and 249 as being one of only three nickeled U.S. revolvers found in the Rinaldo A. Carr ordnance inspected model serial number range 131208-140361 known to exist in collections today. The other two revolvers are nos. 133125 and 134191. After a careful review it was determined, "The occurrence therefore of nickel plated U.S. Cavalry revolvers was predominantly found in the 1870s. Their 'popularity' began to dwindle during the 1880s and was nearly gone during the 1890s" (page 249). The accompanying factory letter for this Cavalry Model states it was chambered in .45 caliber and had a blue finish when it was sold to the U.S. government and delivered to the U.S. government inspector at the Colt plant on January 20, 1891. This delivery was for 200 units. The barrel length and stocks are not listed in the records, a common indication of a 7 1/2 inch barrel and walnut stocks as these features were standard and are the features found on this revolver. The barrel has the one-line Hartford address. The left side of the frame has the two-line patent dates marking followed by "US." Carr's "RAC" inspector initials appear on the barrel, cylinder, frame, and bottom of the grip. A "P" proof appears on the barrel and cylinder. The grip has the date "1891" (faint) and Inspector Stanhope English Blunt's script letter cartouche on the left side and Carr's script letter cartouche on the right side. The matching full serial number is on the frame, trigger guard, and back strap. The matching partial serial number "7603" is on the cylinder and barrel.