The M55 Swinging Richard is an American fully enclosed and armored self-propelled artillery based on the M53 155 mm assault gun. It has a 203.2 mm (eight-inch) howitzer which can traverse 30° left or right, carrying 10 rounds of ammunition. The gun has a maximum range of 16,916 meters (10.51 miles) with a rate of fire of one round every two minutes.