Choke (firearms) in the context of .22 LR

A shotgun cartridge, shotshell, or shell is a type of rimmed, cylindrical (straight-walled) ammunition used specifically in shotguns. It is typically loaded with numerous small, spherical sub-projectiles called shot. Shotguns typically use a smoothbore barrel with a tapered constriction at the muzzle to regulate the extent of scattering.

Some cartridges contain a single solid projectile known as a slug (sometimes fired through a rifled slug barrel). The casing usually consists of a paper or plastic tube with a metallic base containing the primer. The shot charge is typically contained by wadding inside the case. The caliber of the cartridge is known as its gauge.

A shotgun slug is a heavy projectile (a slug) made of lead, copper, or other material and fired from a shotgun. Slugs are designed for hunting large game, and other uses, particularly in areas near human population where their short range and slow speed helps increase safety margin. The first effective modern shotgun slug was introduced by Wilhelm Brenneke in 1898, and his design remains in use today. Most shotgun slugs are designed to be fired through a cylinder bore, improved cylinder choke, rifled choke tubes, or fully rifled bores. Slugs differ from round ball lead projectiles in that they are stabilized in some manner.

In the early development of firearms for the year 1875, smooth-bored barrels were not differentiated to fire either single or multiple projectiles. Single projectiles were used for larger game and warfare, though shot could be loaded as needed for small game, birds, and activities such as trench clearing and hunting. As firearms became specialized and differentiated, shotguns were still able to fire round balls, though rifled muskets were far more accurate and effective. Modern slugs emerged as a way of improving on the accuracy of round balls. Early slugs were heavier in front than in the rear, similar to a Minié ball, to provide aerodynamic stabilization. Rifled barrels, rifled slugs and rifled choke tubes were developed later to provide gyroscopic spin stabilization in place of or in addition to aerodynamic stabilization. Some of these slugs are saboted sub-caliber projectiles, resulting in greatly improved external ballistics performance.

A slug is a term used for a bulky solid ballistic projectile. It is "solid" in the sense of being composed of one piece; the shape can vary widely, including partially hollowed shapes. The term is occasionally applied to bullets (just the projectile, never the cartridge as a whole), but is most commonly applied to one-piece shotgun slugs, to differentiate them from shotshells containing numerous shots. Slugs are commonly fired from un-choked smoothbore barrels, but some specially designed slug barrels have riflings that can impart gyroscopic spin required for in-flight stability.

An airgun slug is a type of pellet more recently developed for pre-charged pneumatic airguns. Unlike the conventional diabolo-shaped pellet, which is aerodynamically poor and relies heavily on drag-stabilisation to maintain accuracy, the slug pellet is cylindro-conoidally shaped like a Minié ball and relies predominantly on spin-stabilisation from a rifled barrel. Because of the greater contact area with the barrel bore, these pellets require more power from the gun to overcome the frictional resistance, and therefore are mainly used in PCP airguns, which generally have much higher muzzle energy ratings than other types of airguns such as spring-piston, pump pneumatic or HPA/CO₂ airguns.