In current usage a riot gun or less-lethal launcher is a type of firearm that is used to fire ""non-lethal" or "less-lethal" ammunition for the purpose of suppressing riots. Less-lethal launchers may be special purpose firearms designed for riot control use, or standard firearms, usually shotguns and grenade launchers, adapted to riot control use with appropriate ammunition. The ammunition is most commonly found in 12 gauge (.729 inches) shotguns and 40 mm (1.57 inches) grenade launchers.