Using rejected U.S. M1842 barrels sold at auction by Springfield Armory, Whitney assembled approximately 2,000 .69-caliber rifled muskets that he exchanged with the state of New Hampshire in 1858 for a number of old flintlock muskets owned by that state. These rifled muskets exhibit a number of anomalies from U.S. M1842 musket, although overall length (57.75") and barrel length (42") remain the same as that musket, the bores are rifles with 7 narrow grooves. In addition to dates and inspection marks placed at Springfield, usually bear state ownership mark "NEW HAMPSHIRE" on top of barrel. In finishing these rifled muskets, Whitney utilized a number of parts from other gun makers, including Sharps M1853 "ladder" style carbine rear sights, bands from Robbins & Lawrence P1853 Enfield rifle-musket contract and internal lock parts remaining from his M1841 rifles. Parts that are unique to these arms include iron nosecap and flat lockplate. Lockplates are unmarked, but barrels usually show a letter/number code common to Whitney's production during this period. Despite a production of approximately 2,000 muskets, survival rate for this type of arm is quite low.