Combination gun

Combination guns have a long history in Europe, the Middle East, Asia, and Africa that date back to the early days of metallic cartridge firearms.

The earliest combination guns were called swivel guns, (not to be confused with the more widely known small cannon that is mounted on a swiveling stand or fork and allows a wide range of motion) which used a set of barrels designed to rotate to allow either the rifled or the smoothbore barrel to line up with a flintlock mechanism before firing.

Four-barrel versions known as Vierlings generally have two triggers, and selectors to switch between both the shotgun and rifle barrels.

An interesting combination gun is the United States Air Force M6 Aircrew Survival Weapon and its civilian version, the Springfield Armory M6 Scout, an all-metal folding combination gun in .22 Hornet over .410 bore or .22 Long Rifle over .410 bore.

The German and Austrian cape guns have the rifled barrel on the right side, which is fired by the front trigger.

The most common layout was a side-by-side shotgun with a centerfire rifled barrel centered on the bottom, such as the M30 Luftwaffe Drilling.

A similar arrangement of a side-by-side shotgun with a rifled barrel centered on top, generally a .22 rimfire caliber or .22 Hornet, was also fairly common.

This requires more precision than regulation of double-barreled shotgun barrels, which are used at shorter ranges with wide patterns of shot where a small misalignment won't be significant.

It was developed by the Soviet Union as a survival gun for their cosmonauts, and was in use from 1986 to 2006, when it was retired because the unique ammunition it uses had degraded too far to be reliable.