Colt Model 1851 Navy revolver manufactured in 1857 as part of the Ordnance Department contract for nearly 17,000 revolvers delivered to the U.S. Army between 1855 and 1859. Many of these Model 1851 "Army/Navy" revolvers were initially issued to the newly formed 1st and 2nd U.S. Cavalry regiments stationed on the Texas frontier. The U.S. contract Army/Navy revolvers remained in service throughout the Civil War. This revolver has the Late Third Model features which include: (1) small rounded, brass trigger guard, (2) brass back strap, (3) beveled loading cut-out, and (4) frame and loading level screws that enter from the left side. The right recoil shield lacks the capping channel found on Fourth Model Navy revolvers. The barrel and cylinder have a military blue finish; the loading lever, frame and hammer are color casehardened; and the trigger guard and back strap have the natural brass finish. The one-piece walnut grip is oil finished. The barrel has a brass cone-shaped front sight and the hammer spur has borderless knurling. The top barrel flat is roll-stamped: "- ADDRESS SAML COLT HARTFORD CT.-" in a single line. The left side of the frame is roll-stamped: "COLTS/PATENT" in two lines with a small "U.S." property mark stamped below it. The cylinder is roll-engraved with the Texas Navy battle scene, "COLT'S PATENT No." and "ENGAGED 16 MAY 1843". The right side of the grip is stamped with the Ordnance final inspection mark which consists of the script initials "WAT" enclosed in an oval border while the left side of the grip is stamped with the Ordnance sub-inspection mark with the script initials "CGC" in a rectangle with rounded ends. "C" Ordnance sub-inspection marks are stamped on the top of the back strap, left grip heel, trigger guard, and top barrel flat. An "H" sub-inspection mark is stamped in two locations on the cylinder and on the left side of the barrel lug. A "K" Colt sub-inspection mark is stamped on the left side of the trigger guard bow, and "M" is stamped on the left trigger guard flat. The full serial number "79917" is stamped on the cylinder, barrel lug, frame, trigger guard and back strap. The partial serial number "9917" is stamped on the loading lever. All of the visible serial numbers match.