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A U.S. Marine holding an American model M-32 6-shot 40 mm launcher, which can be used as a grenade launcher or riot gun depending on the ammunition used.

A riot gun or less-lethal launcher is a type of firearm that is used to fire "non-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. Many of them are 40 mm or 37 mm (about 1.5 inches) caliber.


Less-lethal launchers can fire various sorts of ammunition:

  • Impact projectile. These rely on kinetic energy, e.g. rubber bullets.
  • Teargas cartridge, chemical riot control agent.
  • Pepper spray, chemical riot control agent.
  • Stun ammo
  • Smoke round
  • Shotgun shell.
  • Explosive. Largely for military use.
  • Incendiary. Largely for military use.
  • Sound 180db Sound emitting electric Projectile
  • GLIMPS (Grenade-Launched Imaging Modular Projectile System). This is a 40 mm caliber projectile which contains a small camera which transmits television images of what it sees.

To avoid breaking the projectile up, less-lethal cartridges are often propelled by black powder, which when fired may make an eruption of sparks and smoke which is spectacularly large to those accustomed to modern cartridges propelled by more modern propellants.

Chemical agent ammunition

Chemical agents may be dispersed in three ways:

Muzzle dispersion

This method is the simplest: the chemical agent is in the form of a loose powder, which is expelled by the propellant of the cartridge. These rounds are used at short range, and have effect from the muzzle to a range of about 30 metres (33 yards). This method is best used by operators wearing gas masks, as the chemical agent can easily be blown towards the operator.

Canister projectiles

These are also called gas grenades, and are used at longer ranges. They are analogous to rifle grenades, providing increased accuracy and range over hand-thrown gas grenades. Gas grenades may be used by operators without gas masks, as the agent is only dispersed in the area of impact, as far away as 150 yards (140 m). The agent in gas grenades is dispersed as a gas or an aerosol spray.

Ferret rounds

These are specialized gas grenades designed to penetrate light barriers, such as windows, hollow core doors, and interior walls, and disperse chemical agents on the far side.

Impact rounds

Impact rounds come in a variety of shapes, sizes and compositions for varying roles. Impact rounds are made out of materials of much lower density than the lead normally used in bullets, are larger, and are fired at lower velocities. Rounds are designed with low mass, moderate velocity, and large surface area to prevent the rounds from penetrating the skin significantly or causing severe injury, so they merely provide a painful blow to the target: but instances have been reported where rubber or plastic bullets have caused significant injuries to the body or eyes, and in some cases caused death.[1]

One broad classification of impact rounds is direct fire and indirect fire rounds. Direct fire rounds can be fired directly at the target, ideally targeted low on the target, away from vital organs that are more prone to damage from the impact. Indirect or skip fire rounds are intended to be fired into the ground in front of the target, where they dissipate some energy, and then rebound into the target.

Baton rounds

Baton rounds, often called rubber bullets or plastic bullets, are cylinders made of rubber, plastic, wood, or foam, and can be as large as the full bore diameter of the launcher. Smaller baton rounds may be encased in a shell casing or other housing. Baton rounds may fire one long baton, or several shorter batons. Harder or denser baton rounds are intended for skip fire, while softer or less dense batons are intended for direct fire. Baton rounds are the subject of significant controversy, due to extensive use by British and Israeli forces, resulting in a number of deaths.

Beanbag rounds

Beanbag rounds consist of a tough fabric bag filled with birdshot. The bag is flexible enough to flatten on impact, covering a large surface area, and they are used for direct fire. Beanbag rounds may be wide and flat, designed for close range use, or elliptical in shape, with a fabric tail to provide drag stabilization, for longer range use.

Rubber buckshot

Two rounds of Fiocchi 12 gauge rubber buckshot

These, also called stinger rounds, consist of a number of rubber balls ranging from around 0.32 to 0.60 inches (8.1 to 15.2 mm) in diameter, and are used for direct fire. The small diameter means that each ball contains far less energy than a baton round, but it also limits the range. Rubber slugs, used in 12 gauge firearms, consist of a fin stabilized full bore diameter rubber projectile. These are used for long range, accurate direct fire shots on individual targets.

Pepperball rounds

Pepper-spray projectiles, commonly called pepperballs, are direct-fire paintball-like capsules filled with a pepper spray solution of capsaicin. They provide a longer range, more user-friendly way to disperse pepper spray. Many sorts can be fired from paintball markers. Other sorts are designed to be fired from specially-designed pepperball guns whose muzzle velocity is greater than a paintball marker: if the velocity is not high enough the projectile will not break. As with paintball impacts, the capsule's impact is mildly painful and by itself can discourage rioters, but the pepper spray incapacitates and discourages more rioters than the capsule's impact.

Types of less-lethal launchers

Purpose-built launchers are commonly large bore guns, formerly 25 to 27 mm, modern versions are 37 to 40 mm. Dual-purpose guns are usually 12 gauge (18.5 mm) riot shotguns, firing special less-lethal shotgun shells.

Single-shot large bore launchers, such as the Milkor Stopper 37/38 mm riot gun, M79 Grenade launcher and ARWEN ACE, are generally break open designs. The barrels are relatively short, resulting in a carbine sized gun, and may have a shoulder stock and/or a forward handgrip to provide greater control. Pistol launchers do exist, but they are generally only used for short range, muzzle dispersing chemical agents.

Multishot large-bore launchers, such as ARWEN 37, are usually in the form of a revolver holding five or six rounds in the cylinder. Unlike normal revolvers, the cylinder of a revolving riot gun is too massive to be turned easily by the trigger pull, and is usually turned by a pre-tensioned spring or by a pump action.

Shotguns used for riot control are nearly always in 12 gauge, as that is the gauge in which nearly all riot control rounds are made. Generally riot shotguns are used, such as some models of the Remington 870 and Mossberg 500. Due to the reduced power of riot control rounds, there is insufficient energy to cycle the actions of gas operated and recoil operated firearms, so riot shotguns are manually operated, usually pump action. The advantage of using a riot shotgun for riot control is that the shotgun is a dual use firearm, and can switch quickly to and from the riot control role by changing the ammunition. The downside is that it can fire lethal projectiles, and so extra care must be taken in its use to prevent the wrong ammunition from being used.

A recent addition to the class of riot guns is the pepper ball gun, an example of which is the FN 303. This is essentially a paintball marker, either purpose built for riot control, or modified from a commercial paintball marker. The pepper ball guns use special pepper spray ammunition based on paintball technology, consisting of a gelatin capsule filled with the riot control agent. The guns use compressed gas and provide semiautomatic fire, and the pepperballs act just like paintballs, fracturing on impact and splattering the chemical agent on impact. These can be used for direct fire, to break the balls on the target, or indirect fire, breaking near the target and spraying the agent into the target's vicinity.

Police have been known to use paintball guns loaded with paint projectiles, to mark particular rioters so that police can easily identify and arrest them later.

Some weapons discharge teargas as a solution in water: see Category:Teargas solution squirters.

Legal issues

Large-bore launchers are classified as firearms in most countries. Shotguns intended for riot use are semi-automatic shotguns subject to relevant regulations. Riot control ammunition may be restricted in various jurisdictions, to a lesser or greater degree than normal shotgun shells.


In the U.S. large-bore launchers are subject to BATFE regulations. Since firearms over .50 caliber (13 mm) with rifled barrels are considered destructive devices under the National Firearms Act, only smoothbore riot guns may be sold to civilians; a common form found on the civilian market are M203 grenade launcher replicas, which can be used to fire 37 mm practice rounds. The 40 mm guns are usually rifled, and may fire 40 mm grenades; explosive grenades rely on the spin both for stabilization and for arming the fuze.[2]


Riot guns have been documented to be lethal in some cases. The death of American baseball fan Victoria Snelgrove is one such incident.


Name Caliber Capacity Notes
ARWEN 37 37 mm 5 drum magazine[3]
ARWEN 37S "Shorty" CQB 37 mm 5 Short barrel, no stock, drum magazine[4]
ARWEN ACE 1 single shot, telescoping stock[5]
CM-55 gas gun 37 mm 1 [6][7]
Cobray 37 mm launcher 37 mm 1 aluminum barrel, retractable stock[8]
Defense Technology 37 mm Launcher 37 mm model dependant single-shot and multi-shot versions[9]
DPMS M-37 flare launcher 37 mm 1 [10]
Federal Labs 37 mm rotary gas gun 37 mm 6 rotary drum magazine, top-folding stock[11]
Federal Labs 37 mm single-shot Federal Riot Gun 37 mm 1 [12]
FN 303 18 mm 15 drum magazine
Heckler & Koch launcher 37 mm 1 retractable stock[13]
Hilton multi-purpose gunHolding Dine Lanzador de Gases 37 mm 1
Holding Dine Lanzador de Gases 37 mm 1
M203 grenade launcher 40 mm 1 underslung attachment for rifles
M79 grenade launcher 40 mm 1 break-action
MGL-MK1 40 mm multi-launcher 40 mm 6 rotary drum magazine[14]
Milkor Stopper 37/38 mm riot gun 37/38 mm 1 break-action
MK40 40 mm under barrel launcher 40 mm 1 fits under rifle barrel[15]
MSRG-38 37 mm 6 rotary magazine
Ramo RT 37 37 mm 1 [16]
MK40 40 mm under barrel launcher 40 mm 1 fits under rifle barrel[15]
Russian single shot launcher RGM-40 "Kastet" 40 mm 1 [17]
Sage Control Ordnance SL1 37 mm 1 [18]
Sage Control Ordnance SL6 37 mm 6 rotary magazine[18]
TW73 1 breech loading
Webley Schermuly 37 mm 1


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