Also known as the Enfield Mark III Ball cartridge, the 476 was introduced in 1881 due to concerns regarding the Mark II .455 caliber round properly engaging the rifling of the Enfield revolver. Though phased out of British service in 1887, the Woolwich Arsenal continued Mark III cartridge production into the 1890s, and Dum in India produced the cartridge clear into World War One. Colt manufactured an estimated 2,458 Model 1878s in 476 caliber. The included factory letter verifies the caliber, barrel length and hard rubber grips with the finish blue at time of original shipment. The revolver was shipped to Colt's London Agency, London, England, on February 8, 1886 as part of a 100 gun shipment. The top of the barrel is marked with the one Hartford/Pall Mall address and "476 CAL" on the upper left front of the trigger guard. London Proofhouse "crown/V" and "crown/GP" markings are present on the underside of the barrel and alternating on the cylinder behind each flute. The loading gate has the assembly number "15" and the cylinder is not numbered. Fitted with checkered hard rubber grips with the Rampant Colt in an oval at the top and a lanyard ring on the butt. A letter included with the gun confirms that this revolver was once part of the Gary R. Burghoff Collection (best known for his role as Radar O'Rielly on the hit television series M.A.S.H.)

Very fine as factory refinished. The revolver retains 95% of the blue finish with the grip straps thinning to a brown. The grips are excellent with a few minor handling marks and overall crisp checkering. Mechanically functions fine, but is slightly loose.