Slug guns (that is, shotguns shooting a single, solid projectile) are similar to rifles, but they haven't the precision accuracy of a rifle.  If your TV hunter bagged a deer at 125 yards, he was extremely lucky because that's just about the maximum range of a slug gun's slug.

 

Slug guns can be either smooth bore or rifled.  The rifled guns can either have a fully rifled barrel or a screw-in rifled insert at the barrel's muzzle.  The rifled barrel is designed to shoot the SABOT-type of rifled slug.  The sabot (French for "shoe") is a plastic sleeve that surrounds a sub-caliber projectile.  The plastic sleeve, usually a tought plastic like Delrin, is made in sections.  When the shell is fired, the plastic sabot engages the rifling in the barrel to give the slug a stabilizing spin (just like a rifle bullet).  When the sabot slug leaves the barrel, wind resistance peels off the plastic sleeve sections and the sub-caliber projectile flies to the target.

 

Smooth bore shotguns shoot a hollow U-shaped projectile with a hole in the nose called a "Foster"-type slug.  The Foster slug is made of soft lead with a series of slanting ridges that help spin it as it travels down the barrel to stabilize it.  Another type of slug for smooth bores is called the "Brenneke"-type.  This is a solid lead slug, usually with a cone-shaped point, the same slanting ridges for spin, but has its over powder wad attached to the bottom of the slug with a screw.  Both Foster and Brenneke slugs are designed for CYLINDER BORE or OPEN CHOKE barrels.  That is, both the muzzle diameter and chamber diameter of the barrel are the same -- for a 12 ga. barrel this is 0.729 inches.  Trap, skeet, sporting clays, and waterfowl barrels usually have restrictions -- called CHOKES -- in them.  The choke (amounts of "squeeze" varry with the type) can be machined as part of the barrel or designed as a screw-in sleeve.  Either way, Foster or Brenneke slugs should not be fired in any kind of barrel other than CYLINDER BORE or OPEN CHOKE.

 

IF YOU FIRE A SABOT SLUG IN A BARREL WITH A CHOKE (OR SCREW-IN CHOKE TUBE) YOU WILL BLOW-UP YOUR BARREL, LIKELY DAMAGE YOUR SHOTGUN, AND SEND YOURSELF TO THE EMERGENCY ROOM.  THE PLASTIC SABOT WILL NOT COMPRESS LIKE THE LEAD FOSTER OR BRENNEKE SLUGS.  THE LEAD SLUGS ARE FORGIVING, BUT NOT ACCURATE.  THE PLASTIC SABOTS ARE NOT FORGIVING AND WILL DESTROY YOUR SHOTGUN.