Manufactured in 1857 and purchased by the U.S. Army prior to the Civil War. These U.S. Model 1851s were primarily issued to the 1st and 2nd Cavalry Regiments and were used extensively in campaigns against hostile Indians prior to the Civil War and were found in the 42,000 to 80,000 serial number range. The top barrel flat is marked "-ADDRESS SAML COLT HARTFORD CT.-", and "COLTS/PATENT" over "U.S." is on the left side of frame. The left trigger guard shoulder is marked with a letter "M," and "K" is on the upper left front of the trigger guard bow. The renumbered to match cylinder is roll engraved with the Texas naval battle scene and an "S." The left side of the barrel lug, top of the back strap and behind the trigger guard bow are marked with an "S". The matching serial number is marked on the barrel lug, frame, trigger guard, cylinder and back strap, and the partial serial number "317" is marked on the arbor pin, "173" on the wedge and "3173" on the loading lever.