Gun maker Christian Sharps patented the basic design for the Sharps Pepperbox in 1859. It used 4 barrels arranged in a square pattern. The barrels slid forward on the frame for loading and were then locked into place for firing. The gun is unusual in that the barrels did not rotate. Instead, the firing pin on the hammer face was rotates by the use of a pawl on the side of the hammer, firing a different barrel each time the gun is cocked.. This design was somewhat more reliable than conventional revolvers of the era and gave rise to many imitations. Hiram fires the smallest Sharps, a .22 caliber, in the muling station sequence.