Weapons technology in the U.S. changed radically in the 1850's with the adoption of the 'American system' which was an assembly line technique to manufacture weapons of war. The other major change was rifling rather than smooth bore rifles and the Minie ball ammunition. The U.S. eventually had almost 1.5 million Springfield rifles and over 400,000 British Enfield rifles by war's end. For cavalry, the Sharps breech loader became the weapon of choice. Rifled artillery was also introduced and its greater distance and accuracy was pivotal at Gettysburg. Although the North had more guns, it was a massed artillery barrage by 130 Confederate guns during the battle that would be the largest bombardment of troops in North America.