In October 1863, Whitney secured a contract with U.S. War Department to produce 15,000 U.S. M1861 rifle-muskets. Arms manufactured under this contract conform in all respects to Springfield Model adopted in 1861. The 40" barrel in .58-caliber and rifled with 3-grooves; rear sight conforms to two-leaf model with stepped side walls. Nosecap is M1861 style and made of malleable iron. Socket bayonets furnished with them conform to U.S. M1855/M1861 pattern. Marks include "US" on buttplate and standard inspection marks on barrel and stock. Lockplate marked with eagle surmounting letters "US" forward of hammer and "WHITNEYVILLE" on forward projection of plate; date, "1863" or "1864" stamped on tail of plate.