John H. Hall (gunsmith)
John Hancock Hall (January 4, 1781 – February 26, 1841) was the inventor of the M1819 Hall breech-loading rifle and a mass production innovator. Early life. Hall was born in 1781 in Portland, Maine. He worked in his father's tannery until setting up his own woodworking and boat building shop in 1810 where he tinkered with guns in his spare time. He had taken an interest in firearms during militia service and focused on increasing the rapidity of loading. Career. On May 21, 1811, Hall patented a single shot, breech-loading rifle in collusion with  Washington, D.C. architect Dr. William Thornton. He began manufacturing his new rifles at the rate of 50 per year until the Ordnance Corps (United States Army) ordered 200 rifles in December 1814. He regretfully turned down the contract because he was unable to meet the Army delivery deadline of 1815. Hall recognized individually fitted parts as the factor slowing rifle production and adapted his breech-loading design to the “uniformity principle,” widely known as interchangeable parts. Hall proposed the concept of interchangeable parts to the Army in June 1816 and earned a contract for 1,000 of the "Model of 1819