Riot shotgun A riot shotgun is a shotgun designed or modified for use as a primarily defensive weapon , by the use of a short barrel and a larger magazine capacity than shotguns marketed for hunting . The riot shotgun is used by military personnel for guard duty and was at one time used for riot control , and is commonly used as a door breaching and patrol weapon by law enforcement personnel , as well as a home defense weapon by private citizens . Guns of this type are often labeled as breaching shotguns , tactical shotguns or special - purpose shotguns to denote the larger scope of their use , however these are largely marketing terms . Characteristics . The primary characteristic of a riot shotgun is a " short " barrel ( generally 14 to 20 " long ; 18 " is the shortest length available in the U . S . that is not subject to additional federal BATFE regulation , though such restrictions are rarely a problem for police departments and thus shorter - barrel shotguns are not uncommon among police ) which makes the shotgun more compact and easier to handle , easier to stow inside a police vehicle , and more suitable for quick aiming at ( close ) stationary targets . Generally they have an open ( cylinder - bore ) choke , to permit the shot to spread quickly and to allow use with other types of projectiles , and they may be equipped with bead , rifle , or ghost - ring sights . Riot guns are most often pump - action due to this design ' s lower cost and higher reliability , although in recent years a number of semi - automatic shotgun s designed primarily for defensive use have become available and are used by military , law enforcement and civilians alike . Most riot guns are chambered in 12 - gauge and can handle either 2 . 75 " " standard - length " or 3 " " magnum " cartridges . Most non - shotshell loads , such as less lethal ammunition like bean bags , are made only in 12 - gauge . However , 20 - gauge and . 410 shotguns in riot gun configuration are available . Smaller bores are popular for home defense , as the reduced power and recoil make them more suitable for less experienced shooters who are recoil - sensitive . While most hunting shotguns hold between 2 to 5 shells ( often 3 shells , to comply with U . S . regulations for migratory bird hunting ) , riot shotguns can have a magazine tube as long as the barrel , allowing for 6 to 10 shells to be loaded depending on the model , barrel length , and type of shells loaded . Configurations of grips and stocks for riot shotguns vary widely , but often feature reinforced plastic " furniture " instead of the wood common on hunting firearms . Wood was used for riot gun stocks in the past , and sometimes still is . As compared to hunting shotguns , riot guns more often feature pistol grips , with or without a shoulder stock . Without a shoulder stock ( or with a folding stock ) , a riot shotgun becomes more compact and thus is able to be brought to bear more rapidly in very close quarters . With the stock , the pistol grip facilitates control of the weapon and provides a more ergonomic grip when the shotgun is fired from the shoulder . Foregrips , or forends , also vary , often with the inclusion of a pistol - grip fore - end ( further increasing control and absorbing recoil ) , and / or the addition of an accessory rail or other mounting point for a tactical light . The multiple projectile ability of a shotgun greatly increases the probability of a hit on an assailant , and the multiple projectiles increase the likelihood of a disabling hit . Though many sizes and configurations of shotshell are used by police , among the most common is the 12 - gauge 2 - inch ( 70 mm ) 00 ( " double - ought " ) buckshot shell , which consists of 8 or 9 . 33 caliber ( 8 . 5 mm ) round lead balls , each of which is similar in size and velocity to a 9mm / . 38 caliber handgun bullet ( which actually have a diameter of . 354 - . 357 " ) . This shot spreads out to a greater or lesser degree depending on the barrel choke , and can be effective at ranges as far as 75 yards ( 70 m ) . Also popular is the # 4 buckshot load , which sacrifices individual pellet size ( each pellet is about . 24 caliber ) for greater numbers ( usually 21 pellets per shell ) and is very effective at most indoor ranges ( < 50 feet ) , where the shot has less distance in which to scatter and thus hits the target in a relatively localized pattern . " Deer slugs " ( 1 oz rifled slugs ) provide a powerful , accurate shot with minimal spread , but more risk of overpenetration . " Hybrid " loads combining different sizes of shot , or a slug and shot , are available but less common . These cartridges generally advertise a compromise or " best of both worlds " between the power of slugs or buckshot and the spread of smaller pellets . The delivery of the large number of projectiles simultaneously makes the shotgun the most effective short range weapon commonly used , with a hit probability 45 % greater than a submachine gun , and twice as great as an assault rifle . The ability to use shotgun slug s extends the range and penetration capability of the shotgun . Police officers in the US commonly secure a shotgun in their vehicles , for use when armed resistance is expected or at any time greater firepower than the officer ' s sidearm is needed . Riot vs . combat shotguns . The division between the riot shotgun and the combat shotgun is blurry , and may be more a matter of application than design . A combat shotgun would be used in military combat situations as a primarily offensive weapon , where a riot shotgun would be used in law enforcement or civilian situations as a primarily defensive weapon . Common additions to a combat shotgun would be provision for attaching a bayonet , and the addition of a ventilated heat shield over the barrel ( though this heat shield is a common addition to riot shotguns as well ) designed to prevent the operator ' s fingers from being burned by a barrel heated by multiple shots , and thus to allow the operator to secure a full grip on the weapon while using the attached bayonet , even when the barrel was far too hot to touch ( otherwise , there is little reason to enshroud the barrel and hinder the cooling airflow ) . One or both of these features can be seen on many military long - arms , including the 1903 Springfield , the SMLE , M1 Garand , and Mauser rifles , to name some of the more obvious types . The U . S . Army specifications for shotguns require a metal trigger guard for durability , which reduces the number of " special purpose " models used by police that would also be suitable for the military ( the Mossberg 590 A1 and Benelli M1014 are the standard - issue pump and semi - auto shotguns currently in service ; the standard Mossberg 500 and 590 models , and most variants of the Remington 870 , have plastic trigger groups ) . Riot shotguns are also more limited in range than combat shotguns by the nature of their use . A combat shotgun is considered effective out to 75 yards ( 70 m ) because on average at least 1 pellet of a 9 pellet 00 buckshot load will hit a human sized target at that range . This is enough to degrade the combat effectiveness of an enemy soldier , but it is not enough to reliably disable an assailant in a defensive situation . For that , there must be multiple hits to the target , enough that one or more pellets will hit a vital region . Generally this is well under 40 yards ( 37 m ) with a cylinder bore barrel . Beyond this range , slugs and good iron sight s are recommended , extending the range to over 100 meters . Less lethal alternatives . The latter part of the 20th century saw a new role for the riot shotgun , with the advent of a wide variety of less lethal ammunition for police use . These vary from the early " bean bag " shooting flexible baton round s , rubber bullets and other impact munitions , to tear gas and , released in October 2009 , a 12 gauge electroshock weapon from TASER International . Using the shotgun as the delivery system allows the officers to quickly choose a lethal or a less lethal weapon , so responding officers can adapt to changing situations ; An officer in a standoff can quickly eject a chambered buckshot cartridge and replace it with a less - lethal cartridge such as a bean bag , and is not required to unload the magazine as with most rifles or handguns . Alternatively , one officer can be equipped with less lethal munitions , while others , equipped with buckshot , can provide a backup in case the less lethal rounds fail to stop the target . Entry and breaching shotguns . The entry shotgun or breaching shotgun is a role that can be filled by a standard riot shotgun , or one further modified for these purposes . They may have an extremely short barrel ( 14 " or less ) and often only a pistol grip rather than a buttstock , or a folding or collapsing buttstock if it is provided with one . In addition , the barrel often has a muzzle brake , used to disperse hot gases that might otherwise be deflected toward the shooter . This type of shotgun is designed to fire special breaching round s which are designed to disable or destroy door latches while limiting overpenetration of the projectiles used beyond the door . Since these shotguns would in most areas be classified as short barreled shotguns , they are highly restricted under gun control laws such as the National Firearms Act and generally only used by police and military .