Between 1823 and 1841, a transplanted New Englander named John Hall manufactured an innovative breech-loaded rifle at a new government rifle factory established at Harpers Ferry near the Armory. Hall demonstrated in 1826 that rifles of his design and production could be made with interchangeable parts with the aid of over sixty-three inspection gauges and sophisticated machinery. His flintlock rifle, incorporating a pivoting breech-loading receiver, was adopted by the US Army as the Hall’s Rifle US Model 1819.

In 1834, another New Englander, Simeon North, a private arms contractor in Middletown, Connecticut, took Hall’s achievement one step further. Using Hall’s gauges, he produced rifles that were practically interchangeable with those made by Hall at Harper’s Ferry. For the first time, two different and distant production centers had produced practically interchangeable arms by adopting uniform practices.  Production of Halls’ rifles was ended in 1844.