Railguns are ballistic weapons using electromagnetics rather than chemical propellants to to launch projectiles. They first appears on a Bolo with the Mark II as Infinite Repeaters and a 165mm railgun was adopted as the main gun of the Bolo Mark IV . Typically they fired depleted uranium long-rod penetrators, but specialised cluster, incendiary, chemical and fuel-air rounds were also available for use. With minor modifications, including several increases in size, railguns were used as the main gun of Bolo tanks for two centuries but the development of the Mark X with its Laser Cannon spelled its end. Although the Mark XI , developed in parallel, used a 18cm railgun and enjoyed a long and successful career, it was the last Bolo to use a railgun as its primary anti-armour role.