The primary characteristic of a riot shotgun is a "short" barrel (generally 14 to 20 inches (360 to 510 mm) long; 18 in (460 mm) is the shortest length available to civilians in the U.S. that is not subject to additional federal ATF regulation) 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.
Smaller bores are popular for home defense, as the reduced power and recoil make them more suitable for less experienced shooters who may be more recoil-sensitive.
For example, the popular Remington 870 Police model riot shotgun often ships and is used with the stock four-round magazine tube by Law Enforcement personnel.
[5] Configurations of grips and stocks for riot shotguns vary widely, but often feature reinforced plastic "furniture" instead of the wood common on hunting firearms.
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.
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).
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 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 590A1 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).
These vary from the early "bean bag" shooting flexible baton rounds, rubber bullets and other impact munitions, to tear gas and, released in October 2009, a 12 gauge electroshock weapon from TASER International.
In addition, the barrel often has a muzzle brake, used to disperse hot gases rearward, in order to reduce recoil.
In addition, many people suffered minor injuries (nose and finger fractures, hemorrhagic bruises), and a few needed permanent psychological help because of the shock.