Rifled Slug When you're hunting animals with tough hide and bone like bear or hogs you need a robust, reliable slug to get the job done. When Federal Premium set out to make the smoothbore slug more effective for the standard slug slinger, the Vital-Shok Slug TruBall system was created. Weメve reinvented, redefined slug technology and that means you can upgrade without changing barrels. For 2010, we add a new 12-gauge TruBall Deep Penetrator slug. This is much harder (higher antimony) lead than the traditional TruBall and features a more distinct shoulder for extra toughness. They are designed for an impressive 18-20 inches of penetration.