Riot gun 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 shotgun s and grenade launcher s , adapted to riot control use with appropriate ammunition . Many of them are 40 mm or caliber . Ammunition . Less - lethal launchers can fire various sorts of ammunition : 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 . This method is best used by operators wearing gas mask s , 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 grenade s , 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 . 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 . 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 bullet s or plastic bullet s , 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 round s 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 . These , also called stinger rounds , consist of a number of rubber balls ranging from around 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 projectile s , 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 marker s . 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 shotgun s , firing special less - lethal shotgun shell s . 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 . 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 shell s . U . S . . In the U . S . large - bore launchers are subject to BATFE regulations . Since firearms over . 50 caliber ( ) 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 grenade s ; explosive grenades rely on the spin both for stabilization and for arming the fuze . Lethality . Riot guns have been documented to be lethal in some cases . The death of American baseball fan Victoria Snelgrove is one such incident .