New York posted up some pertinent questions. And he's right, a rifled barrel with sabot slugs is right at home at 100 yards, and certain guns can even get it done out to 200 yards.

Now a smooth bore with rifle slugs... with a scope, or at the very least rifled sights, 100 yards is about it for you. It takes a steady hand, and a decent set up. With just a bead, 75 is about all you can realistically expect. The gun is of course capable of killing at ranges MUCH in excess of that, but most guns are not able to shoot accurately enough for ethical results.