Only 1,000 of these rifles were manufactured in 1841-1844 for the U.S. Navy by N. P. Ames. It has a square lug on the bottom of the muzzle for attaching an angular type bayonet, blade front sight on the front barrel band, rear sight groove on the breech lever, "WM. JENKS" and "USN/RP/P/1844" in front of the breech lever and oval loading port. "8/50" and a hand scratched "101" are on the underside of the lever. The lock plate is marked "WM. JENKS" and "N.P. AMES/SPRINGFIELD/MASS." There is an outline of a cartouche visible on the left.