A pneumatic cannon is typically a large-calibre projectile launcher that uses compressed air as a propellant. Other related terms are pneumatic weapon and air gun. It may refer to:

• Spud gun, an improvised launcher, typically made from lengths of pipe, used to project potatoes (aka "spuds"), which sometimes use compressed air as a propellant.
• Dynamite gun, a cannon which uses compressed air to launch explosive shells filled with dynamite, rather than a more conventional explosive propellant.
• Holman Projector, a mortar-like pneumatic or steam-operated air-defense weapon used by the Royal Navy during WWII.
• FN 303, a compressed-air powered less-lethal projectile launcher designed for crowd control.
• Numerous other, similar compressed-air powered projectile launchers, of all varieties.

Other uses:

• The M61 Vulcan, M134 Minigun, or other Gatling-type weapons, which do not propel projectiles by compressed air, but instead sometimes have their operating mechanism powered by bleed air when mounted in certain turbine-powered aircraft; they are typically hydraulically or electrically operated in other applications, without a ready supply of compressed air. This is a rare usage of this term.

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