First and foremost is your marksmanship skill. The skills required to aim and shoot a shotgun are, in this situation, exactly the same as those required to shoot a rifle accurately. You will have to aim the shotgun, not point it—a reversal of how one normally shoots a scattergun. In addition, a shotgun must be equipped with adjustable sights or a scope, so that it can be sighted-in and aimed. You must also know which ammunition will perform best in your shotgun barrel. Time spent on a range to find the right combination is essential. Last but not least is practice. You must become confident in your ability to shoot a shotgun accurately.
A single shotgun projectile is called a slug. The slug is generally a cup-shaped piece of lead approximately the diameter of the bore of the shotgun barrel. A shotgun slug with grooves and ridges on its outer surface is called a rifled slug. Such rifling contributes little to flight stability. The nose-heavy rifled slug gains its stability from its design, which is similar to that of a badminton bird. Slugs can be fired through the barrel of any choke constriction without damaging the choke. This is because the slug is soft lead and the choke is hard steel. A more recent innovation in shotgun ammunition for big game incorporates a pistol bullet design for hunting encased in a plastic cup called a sabot. When used with specially designed rifled barrels, shotguns firing these sabot rounds are capable of acceptable groups out to 150 yards or more.
Any shotgun larger than 20 gauge is adequate for hunting, but the most commonly used gauge for big game is a 12 gauge. Most manufacturers today market shotguns specifically designed for slug shooting.
Slug-shooting shotguns are often referred to as "brush guns," implying that a slug will shoot through brush and maintain its accuracy. However, all projectiles—regardless of whether they are shot from a rifle of a shotgun—are subject to deflection should they strike any foreign object, brush included. Therefore, a shooter must have a clear and unobstructed view of the target in order to fire a safe and accurate shot.
Remember, even though a shotgun slug's accuracy maxes out at around 100-150 yards, it can still travel a distance of nearly 1,000 yards. You must apply all gun safety rules and be sure of your target and what lies beyond it.