TruBall uses simple plastic ball between the wad and slug to increase smooth bore accuracy. Copper-plated deep penetrator slugs made from harder lead. More defined shoulder helps slug get 18-20" of penetration. Larger hollow point. The TruBall rifled slug system locks its components together, centering the slug as it passes through the barrel. The result is groups as small as 1.4 inches at 50 yards the most consistent smoothbore performance possible.