High Quality Content by WIKIPEDIA articles! A shotgun slug is a heavy lead projectile, that may have pre-cut rifling, intended for use in a shotgun and often used for hunting large game. The first effective shotgun slug was introduced by Wilhelm Brenneke in 1898, and his design remains in use today. Most shotgun slugs are designed to be fired through a smoothbore barrel, which means that they must be self-stabilizing and capable of passing through a choked barrel.