A riot gun or less-lethal launcher is a type of firearm
Firearm
A firearm is a tool that projects either single or multiple missiles at high speed thru a controlled explosion. The firing is achieved by the gases produced thru fast, confined combustion of a propellant....
that is used to fire less than lethal ammunition
Ammunition, often referred to as ammunition, is a common term derived from the French language la munition which embraced all material used for war, but which in time came to refer particularly to gunpowder and artillery....
A riot is a type of civil disorder identified by disorganised groups lashing out in a unexpected and intense rash of violence, vandalism or other crime....
s. Less-lethal launchers might be special purpose firearms designed for riot control use, or standard firearms, generally shotgun
A shotgun is a firearm that is often built to be fired from the shoulder, which uses the energy of a fixed shell to launch a number of little round pellets called lead shot, or a solid missile called a shotgun slug....
s and grenade launcher
Grenade launcher
A grenade launcher is a weapon that launches a grenade with more accuracy, higher speed and to greater distances than a soldier could throw it by hand....
s, evolved to riot control use with appropriate ammo. of them are 37 mm or 40 mm caliber
The term caliber designates the interior diameter of a tube, the diameter of a solid wire or rod, or a measurement of the length of a gun relative to its diameter....
(about 1.5 inches ) .
Ammunition
* Impact missile. rubber bullet
Rubber bullet
Rubber bullets are rubber or rubber-coated projectiles that can be fired from firearms. They are usually less than lethal, unless fired at short range, but are frequently sufficiently heavy to pierce skin....
s.
* Teargas cartridge. This and the subsequent are chemical riot control agents.
* Pepper spray
Pepper spray
Pepper spray, AKA OC spray , OC gas, and capsicum spray, is a lachrymatory agent that is used in riot control, crowd control, and private self-defense, including protection against dogs and bears....
* Stun ammo
* Smoke
Smoke
* Shotgun shell
Shotgun shell
A shotgun shell is a self-contained cartridge stuffed with lead shot or a shotgun slug built to be fired from a shotgun. Most shotgun shells are built to be fired from a smoothbore Gun barrel, but with the recent gain in popularity of dedicated shotguns with Rifling barrels for firing slugs, there are several rounds in particular designe...
* Incendiary
Mostly for military use only.
* GLIMPS ( Grenade-Launched Imaging Modular Projectile System). This is a 40 mm caliber
The term caliber designates the inside diameter of a tube, the diameter of a solid wire or rod, or a measurement of the length of a gun relative to its diameter....
missile which has a tiny camera which transmits TV images of what it sees. See this link. Great antiriot systems from
MGL-140 
