Ames manufactured 4,250 of these distinctive "mule ear" breech loading carbines between 1843-1846. The Jenks carbines were originally smoothbores with a round loading aperture. Around 1861, most Jenks carbines were rifled and had the loading aperture enlarged to an oval shape to accept a paper cartridge rather than loose balls and powder. "Wm JENKS" and "U.S.N./RC/P/1845" marked on the top of the barrel at the breech ahead of the loading aperture. Sling ring mounted on the lower tang. Oval script "RC" (Rufus Chandler) and boxed script "JL" (Joseph Lanman) inspection cartouches stamped on the left of the stock.