Very good info Rick. I would like to add that the reason a Foster-type (rifled slug) has rifling is because smooth-bore barrels do not impart spin on the projectile as you mentioned. Since the smooth-bore does not impart a stabilizing spin on the projectile, the projectile has rifling to impart it's own spin. To fire a rifled slug through a rifled barrel will result in the rifling of the barrel and the slug itelf "fighting" each other.The rifled slug was introduced by the German company RWS in 1898. This slug is the Brenneke, and still available today from Rottweil. In 1936 Winchester introduced the "Foster" slug. The Brenneke is solid lead with a series of lead cards attached to the base, while the Foster slug has a hollow base, not unlike the old Minnie-ball projectiles used during the war between the states.Each variant has a set of angled "Rifling" grooves around it's circumference, and works on the same principle as a dart where the weight is forward of the center of air pressure and makes them fly point-forward. A slug, however, does not have fins to stabilize it's flight. It spins at a very slow rate providing better stabilization than shooting a round ball. (You can throw a football with a good spiral much farther and more accurately than you can the baseball "knuckleball" pitch which has no spin on it.)The sabot (pronounced "say-bo") slug, is an hourglass-shaped solid piece of lead encased in two-halves of a plastic sleeve (the sabot). The hourglass shape makes the slug weight-forward as the other types of slugs. When fired, the projectile exits the muzzle, the plastic halves separate falling just yards downrange while the projectile carries on downrange. The sabot projectile is smaller in diameter than a Brenneke or Foster slug, but weighs close to the same. As the slug itelf has no rifling, it requires stabilization to be imparted via rifling grooves in the barrel.Do not confuse the two, and most certainly do not interchange the two. The advice in Rick's post is right on the money and should be followed at all times. Mike RossLife Member, NAHCMember, National Rifle AssociationMember, Meeker Co. Historical SocietyEdited by: MTRoss at: 1/13/03 10:52:33 am