Williams, of Covington, Kentucky, who later served as an artillery captain with a battery of his design.
The hand crank opened the sliding breech which allowed the crew to load a round and cap the primer.
At the end of the war, four examples of this gun were captured to send to West Point.
During the early trials of the gun, the Richmond Daily Exchange dated May 20, 1862, reported that: "General Floyd attended a trial of the Williams' mounted breech-loading rifle, which is claimed will throw twenty balls a minute a distance of fifteen hundred yards".
Some sources say it could fire 65 rounds per minute but accuracy was greatly reduced due to the manual loading.