A slug is a term used for a bulky solid ballistic

projectile A projectile is an object that is propelled by the application of an external force and then moves freely under the influence of gravity and air resistance. Although any objects in motion through space are projectiles, they are commonly found ...

. 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

bullet A bullet is a kinetic projectile, a component of firearm ammunition that is shot from a gun barrel. They are made of a variety of materials, such as copper, lead, steel, polymer, rubber and even wax; and are made in various shapes and constru ...

s (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 choked smoothbore barrels, but some specially designed slug barrels have

rifling Rifling is the term for helical grooves machined into the internal surface of a firearms's barrel for imparting a spin to a projectile to improve its aerodynamic stability and accuracy. It is also the term (as a verb) for creating such groov ...

s that can impart gyroscopic spin required for in-flight stability. An airgun slug is a new type of pellet recently developed for pre-charged pneumatic airguns. Unlike the conventional

diabolo The diabolo ( ; commonly misspelled ''diablo'') is a juggling or circus skills, circus juggling prop, prop consisting of an axle () and two cone, cups (hourglass/egg timer shaped) or cylinder, discs derived from the Chinese yo-yo. This object i ...

-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 A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden stave (wood), staves and bound by wooden or metal hoops. The word vat is often used for large containers ...

. 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 Muzzle energy is the kinetic energy of a bullet as it is expelled from the muzzle (firearm), muzzle of a firearm. Without consideration of factors such as aerodynamics and gravity for the sake of comparison, muzzle energy is used as a rough indi ...

ratings than other types of airguns such as spring-piston, pump pneumatic or

HPA The pascal (symbol: Pa) is the unit of pressure in the International System of Units (SI). It is also used to quantify internal pressure, stress, Young's modulus, and ultimate tensile strength. The unit, named after Blaise Pascal, is an S ...

/ CO₂ airguns. A water-slug refers to operating a

submarine A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or infor ...

's torpedo tube that has been filled with water rather than a

torpedo A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, such ...

, thus shooting a "slug of water." In simulated naval battles and exercises this is to represent the dispatch of an actual torpedo as, to sonar detectors, the sounds are very alike.

References

Projectiles Paramilitary cartridges Shotgun cartridges Ammunition {{Ammo-stub