The U.S. Model 1861 4.5-inch Ordnance Rifle known locally as The Big Gun was furnished by the U.S. War Department in 1893 for the annual Reunion of the Blue and Gray at Mammoth Spring, where it was fired daily at sunrise and sunset during reunion week. The cannon could be mounted on a field carriage for greater mobility or on a longer, heavier siege carriage. Classified as a siege and garrison gun, it was a heavy, long-barreled weapon designed to attack or defend forts or cities at long range. When mounted on a field carriage, it was the largest piece of field artillery used in the Civil War. It fired 30-pound shells to nearly two miles, while average field artillery had a 3-inch bore and fired eight- to ten-pound shells about one mile. The rifled cast-iron tube, bored from a solid piece, weighed 3,569 pounds without the carriage and had a range of 3,265 yards at 10° elevation. Its projectiles included a 25.5-pound Dyer shell and 30-pound Hotchkiss and Schenkl shells, and it could fire 12 to 20 rounds per hour. Cleaned in 2006, it was found to contain a broken rammer in the tube and black powder still in the vent hole, both of which were removed.