The model 1842 was the first regulation percussion musket to be manufactured at both Harper's Ferry Armory and the Springfield Armory. The 1842 model was produced during 1844-1855, with about 275,000 being produced. These were also the last .69 caliber smoothbore arms to be produced by the U.S. government. Approximately 275,000 were manufactured between 1844 and 1855, with nearly two-thirds of these produced at Springfield. The town of Harpers Ferry is nestled into a valley at the confluence of the Shenandoah and Potomac Rivers. Originally located in Virginia, Harpers Ferry became part of the new state of West Virginia in 1863. Harpers Ferry Armory achieved notoriety as the birthplace of what became known as the "American System of Manufacture," in which full interchangeability of precision-made parts between mechanical devices manufactured in more than one location was achieved for the first time. (NRA Museum).