has had only a few innovations. For decades the guns were almost exclusively rifled, but now most new tanks have smoothbore guns. Rifling of the barrel imparts spin on the projectile, improving ballistic accuracy. The best traditional antitank weapons have been kinetic energy rounds, whose penetrating power and accuracy is greatly decreased with the loss in muzzle velocity at extended range. For longer ranges high-explosive anti-tank rounds are more effective, but accuracy is limited; for extremely long ranges cannon-launched guided projectiles (CLGPs) are considered more accurate. The use of the autoloader has been a development favoured by some nations and not others. Some countries adopted it as a means to keep the overall size of the tank down. Interest has also been shown as a means to protect the crew by separating them further from the gun and ammunition. For example, an autoloader allows the use of an unmanned turret in the T-14 Armata. Smoothbore In the 1960s smoothbore tank guns were developed by the United States, the Soviet Union, and later by the experimental American-West German MBT-70 joint project. High-precision smoothbore tank gun barrels were perfected by the US Army’s Weapons Laboratory at the Watervliet Arsenal based on a pair of patents by inventor Albert L. de Graffenried. More than 20,000 tank cannons were manufactured by the Watervliet Arsenal for the US Abrams M1A1 tank using de Graffenried’s patented high-precision manufacturing inventions. Based on their experience with the 2A28 Grom gun/missile system of the BMP-1, the Soviets produced the T-64B main battle tank, with an auto-loaded 2A46 125 mm smoothbore high-velocity tank gun, capable of firing APFSDS ammunition as well as ATGMs. Similar guns continue to be used in the latest Russian T-90, Ukrainian T-84, and Serbian M-84AS MBTs. The German company Rheinmetall developed a more conventional 120 mm smoothbore tank gun which can fire LAHAT missiles, adopted for the Leopard 2, and later the U.S. M1 Abrams. The chief advantages of smoothbore designs are their greater suitability for fin stabilised ammunition and their greatly reduced barrel wear compared with rifled designs. Much of the difference in operation between smoothbore and rifled guns shows in the type of secondary ammunition that they fire, with a smoothbore gun being ideal for firing HEAT rounds (although specially designed HEAT rounds can be fired from rifled guns) and rifling being necessary to fire HESH rounds. The Gulf Wars demonstrated that Abrams M1A1