Manufactured in 1878, the first year of production. The barrel has the scarce "COLT'S PT. F.A. MFG Co HARTFORD CT. U.S.A. DEPOT 14 PALL MALL LONDON" address and is chambered in .450 Boxer. The trigger guard is marked "45 CAL/B." Only 1,653 Model 1878s were manufactured in .450 Box with a 5 1/2 inch barrel and blue finish per Don Wilkerson in "Colt's Double-Action Revolver" (354). London proofs are stamped on the underside of the barrel and behind each cylinder flute. The cylinder and both grip panels are numbered to the gun (right grip panel number faint). The partitioned case features a Colt London paper label on the interior of the lid and contains an added cartridge block holding 28 rounds of .450 caliber, cleaning rod, oiler, case key, and tool.