Combination gun

A combination gun is a break-action hunting firearm that comprises at least one rifled barrel and one shotgun barrel. Combination guns using one rifle and one shotgun barrel usually are in an over and under configuration. Side-by-side versions are referred to as cape guns. A drilling (German for "triplet") is a combination gun that has three barrels. A vierling (German for "quadruplet") has four barrels. Combination guns generally use rimmed cartridges, as rimless cartridges are more difficult to extract from a break-action weapon.

Combination guns have a long history in Europe, Africa, and Asia, dating back to the early days of cartridge firearms. These guns are almost exclusively hunting arms. The advantage of having a single firearm that can fire both rifle and shotgun cartridges is that a single gun can be used to hunt a very wide variety of game, from deer to game birds, and the shooter can choose the barrel appropriate for the target in seconds. As a result, they are popular with gamekeepers who often need the flexibility of the combination gun during their normal duties.

The earliest combination guns were called swivel guns (not to be confused with the more widely known small cannon), which used a set of barrels designed to rotate to allow either the rifled or smooth-bore barrel to line up with a flintlock mechanism. Modern combination guns tend to resemble double-barreled shotguns and double rifles, and are almost universally break open designs. Combination guns generally have a selector that allows the user to choose which barrel will fire. Drillings with two shotgun barrels and one rifle barrel may have two triggers, one for each shotgun barrel, and a selector that will allow one trigger to fire the rifle barrel. Four-barrel versions known as Vierlings generally have two triggers, and selectors to switch each between shotgun and rifle.

Combination guns are over/under designs, usually with a shotgun barrel over a rifle barrel. Iron sights are commonly used for aiming the rifle, and the front sight alone is sufficient to point the shotgun. Scope mounts are available, sometimes with a cutout for aiming the shotgun barrels. However, the thinness of the shotgun barrels that are usually on top make the scope mounting awkward. An interesting combination gun is the Ithaca M6 Aircrew Survival Weapon and a civilian version Springfield Armory M6 Scout, an all-metal folding combination gun in .22 Hornet over .410 bore.

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