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; with this scarce example escaping said alteration and still retaining its original round loading aperture and smoothbore. "Wm JENKS" and "USN/RP/P/1845" marked on the top of the barrel at the breech ahead of the round loading aperture. Single letter inspection initials marked on several components. The lock plate has the Ames three-line marking in the center and "Wm JENKS" towards the rear. This example does not have a fixture for a sling ring as usually seen on the lower tang. Boxed script "RP" (Richard Paine) and "JL" (Joseph Lanman) inspection cartouches stamped on the left of the stock.