The first Gatling gun was invented and built by R.J. Gatling in 1862 and patented in 1865. Colt's Armory in Hartford, Connecticut then produced the weapon for the military. The gun has 10 barrels which revolve inside of a supporting frame. As the barrels revolve, an ingenious mechanism automatically loads cartridges , cocks the hammers, fires each barrel in turn, and ejects the empty shells in one continuous motion, all powered by simple hand-crank turned by the gunner. The Gatling gun used in the film was a genuine antique 45-70 caliber Colt made before 1900 -- and it worked flawlessly.