Single-shot rifle chambered for .22- through .44 rimfire cartridges. Part-octagon barrel from 23" to 28" in length. Breech activated by combination trigger guard action lever. Opening breech automatically ejected empty cartridge. External hammer manually cocked. Featured an adjustable sight. Barrel blued. Case colored frame and walnut stock. Marked, "Allen & Wheelock/ Allen's Pat. Sept. 18, 1860". Approximately 2,000 manufactured between 1860 and 1871.