Technology of the guns themselves has had only a few innovations. Throughout the history of tank guns, they have almost exclusively been rifled weapons, however most modern tanks now use 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 decrease with 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.