The model 1842 U.S. Percussion Musket was produced in great numbers by both the Harpers Ferry and Springfield Armories from 1844 to 1855. The model 1842 was notable in several respects, chiefly that it was the last .69 caliber musket. Additionally, it was the first weapon made at both the Harpers Ferry and Springfield Armory with completely interchangeable parts.
