Slugthrower Shotgun

A shotgun (also known as a scattergun and peppergun, or historically as a fowling piece) is a firearm that is usually designed to be fired from the shoulder, which uses the energy of a fixed shell to fire a number of small spherical pellets called shot, or a solid projectile called a slug. Shotguns come in a wide variety of sizes, ranging from 5.5 mm (.22 inch) bore up to bore, and in a range of firearm operating mechanisms, including breech loading, single-barreled, double or combination gun, pump-action, bolt-, and lever-action, semi-automatic, and even fully automatic variants.

A shotgun is generally a smoothbore firearm, which means that the inside of the barrel is not rifled. Preceding smoothbore firearms, such as the musket, were widely used by armies in the 18th century. The direct ancestor to the shotgun, the blunderbuss, was also used in a similar variety of roles from self defence to riot control. It was often used by cavalry troops due to its generally shorter length and ease of use, as well as by coachmen for its substantial power. However, in the 19th century, these weapons were largely replaced on the battlefield with breechloading rifled firearms, which were more accurate over longer ranges. The military value of shotguns was rediscovered in the First World War, when American forces used 12-gauge pump action shotguns in close-quarters trench fighting to great effect. Since then, it has been used in a variety of roles in civilian, law enforcement, and military applications.

The shot pellets from a shotgun spread upon leaving the barrel, and the power of the burning charge is divided among the pellets, which means that the energy of any one ball of shot is fairly low. In a hunting context, this makes shotguns useful primarily for hunting birds and other small game. However, in a military or law enforcement context, the large number of projectiles makes the shotgun useful as a close quarters combat weapon or a defensive weapon. Shotguns are also used for target shooting sports such as skeet, trap, and sporting clays. These involve shooting clay disks, known as clay pigeons, thrown in various ways.

Characteristics
Shotguns come in a wide variety of forms, from very small up to massive punt guns, and in nearly every type of firearm operating mechanism. The common characteristics that make a shotgun unique center around the requirements of firing shot. These features are the features typical of a shotgun shell, namely a relatively short, wide cartridge, with straight walls, and operating at a relatively low pressure.

Ammunition for shotguns is referred to in the USA as shotgun shells, shotshells, or just shells (when it is not likely to be confused with artillery shells). The term cartridges is standard usage in the United Kingdom.

The shot is usually fired from a smoothbore barrel; another configuration is the rifled slug barrel, which fires more accurate solitary projectiles.

Uses
The typical use of a shotgun is against small and fast moving targets, often while in the air. The spreading of the shot allows the user to point the shotgun close to the target, rather than having to aim precisely as in the case of a single projectile. The disadvantages of shot are limited range and limited penetration of the shot, which is why shotguns are used at short ranges, and typically against smaller targets. Larger shot sizes, up to the extreme case of the single projectile slug load, result in increased penetration, but at the expense of fewer projectiles and lower probability of hitting the target.

Aside from the most common use against small, fast moving targets, the shotgun has several advantages when used against still targets. First, it has enormous stopping power at short range, more than nearly all handguns and many rifles. Though many believe the shotgun is a great firearm for inexperienced shooters, the truth is, at close range, the spread of shot is not very large at all, and competency in aiming is still required. A typical self-defense load of buckshot contains 8-27 large lead pellets, resulting in many wound tracks in the target. Also, unlike a fully jacketed rifle bullet, each pellet of shot is less likely to penetrate walls and hit bystanders. It is favored by law enforcement for its low penetration and high stopping power.

On the other hand, the hit potential of a defensive shotgun is often overstated. The typical defensive shot is taken at very close ranges, at which the shot charge expands no more than a few centimeters. This means the shotgun must still be aimed at the target with some care. Balancing this is the fact that shot spreads further upon entering the target, and the multiple wound channels of a defensive load are far more likely to produce a disabling wound than a rifle or handgun.

Sporting
Some of the most common uses of shotguns are the sports of skeet shooting, trap shooting, and sporting clays. These involve shooting clay discs, also known as clay pigeons, thrown in by hand and by machine. Both skeet and trap competitions are featured at the Olympic Games.

Hunting
The shotgun is very popular for bird hunting, it is also used for more general forms of hunting especially in semi-populated areas where the range of rifle bullets may pose a hazard. Use of a smooth bore shotgun with a rifled slug or, alternatively, a rifled barrel shotgun with a sabot slug, improves accuracy to 100 m or more. This is well within the range of the majority of kill shots by experienced hunters using shotguns.

However, given the relatively low muzzle velocity of slug ammunition, typically around 500 m/s (about 1600 feet per second), and the blunt, poorly streamlined shape of typical slugs (which cause them to lose velocity very rapidly, compared to rifle bullets), a hunter must pay close attention to the ballistics of the particular ammunition used to ensure an effective and humane kill shot.

At any reasonable range, shotgun slugs make effective lethal wounds due to their tremendous mass, reducing the length of time that an animal might suffer. For example, a typical 12 gauge shotgun slug is a blunt piece of metal that could be described as an 18 mm (.729 inch) caliber that weighs 28 grams (432 grains). For comparison, a common deer-hunting rifle round is a 7.62 mm (.308 inch) slug weighing 9.7 grams (150 grains), but the dynamics of the rifle cartridge allow for a different type of wound, and a much further reach.

Shotguns are often used with rifled barrels in locations where it is not lawful to hunt with a rifle. Typically, a sabot slug is used in these barrels for maximum accuracy and performance. Shotguns are often used to hunt whitetail deer in the thick brush and briers of the Southeastern and upper Midwestern United States, where, due to the dense cover, ranges tend to be very close - 25 m or less.

Sabot slugs are essentially very large hollowpoint bullets, and are streamlined for maximum spin and accuracy when shot through a rifled barrel. They have greater ranges than older Foster and Brenneke-type slugs.

Law Enforcement
In the US and Canada, shotguns are widely used as a support weapon by police forces. One of the rationales for issuing shotguns is that, even without much training, an officer will probably be able to hit targets at close to intermediate range, due to the "spreading" effect of buckshot. This is largely a myth, as the spread of buckshot at 25 feet averages 8 inches, which is still very capable of missing a target. Some police forces are replacing shotguns in this role with carbine rifles such as AR-15s. Shotguns are also used in roadblock situations, where police are blocking a highway to search cars for suspects. In the US, law enforcement agencies often use riot shotguns, especially for crowd and riot control where they may be loaded with less-lethal rounds such as rubber bullets or bean bags. Shotguns are also often used as breaching devices to defeat locks.

Military
Shotguns are common weapons in military use, particularly for special purposes. Shotguns are found aboard naval vessels for shipboard security, because the weapon is very effective at close range as a way of repelling enemy boarding parties. In a naval setting, stainless steel shotguns are often used, because regular steel is more prone to corrosion in the marine environment. Shotguns are also used by military police units. U.S. Marines have used shotguns since their inception at the squad level, often in the hands of NCOs, while the U.S. Army often issued them to a squad's point man. Shotguns were modified for and used in the trench warfare of WWI, in the jungle combat of WWII and Vietnam and are being used today in Iraq, being popular with soldiers and marines in urban combat environments. Some U.S. units in Iraq use shotguns with special frangible breaching rounds to blow the locks off doors when they are making a surprise entry into a dwelling.

Home & Personal Defense
Shotguns are a very popular means of home defense for many of the same reasons they are preferred for close-quarters tasks in law enforcement and the military.

Design features for various uses
Compared to handguns, shotguns are heavier, larger, and not as maneuverable in close quarters (which also presents a greater retention problem), but do have these advantages:
 * They are generally much more powerful.
 * The average shooter can engage multiple targets faster than with a handgun.
 * They are generally perceived as more intimidating.
 * On average, a quality pump-action shotgun is generally less expensive than a quality handgun (self-loading shotguns are generally more expensive than their pump-action counterparts).
 * When loaded with smaller shot, a shotgun will not penetrate walls as readily as rifle and pistol rounds, making it safer for non-combatants when fired in or around populated structures. This comes at a price, however, as smaller shot may not penetrate deeply enough to cause an immediately incapacitating wound; those who recommend birdshot for minimizing wall penetration also suggest backing it up with a larger buckshot if the first shot fails to stop the threat.

Types
The wide range of forms the shotgun can take leads to some significant differences between what is technically a shotgun and what is legally considered a shotgun. A fairly broad attempt to define a shotgun is made in the United States Code (18 USC 921), which defines the shotgun as "a weapon designed or redesigned, made or remade, and intended to be fired from the shoulder, and designed or redesigned and made or remade to use the energy of the explosive in a fixed shotgun shell to fire through a smooth bore either a number of ball shot or a single projectile for each single pull of the trigger."

A rifled slug, with finned rifling designed to enable the projectile to be safely fired through a choked barrel, is an example of a single projectile. Some shotguns have rifled barrels and are designed to be used with a "saboted" bullet, one which is typically encased in a two-piece plastic ring (sabot) designed to peel away after it exits the barrel, leaving the bullet, now spinning after passing through the rifled barrel, to continue toward the target. These shotguns, although they have rifled barrels, still use a shotgun-style shell instead of a rifle cartridge and may in fact still fire regular multipellet shotgun shells, but the rifling in the barrel will affect the shot pattern. The use of a rifled barrel blurs the distinction between rifle and shotgun, and in fact the early rifled shotgun barrels went by the name Paradox for just that reason. Hunting laws may differentiate between smooth barreled and rifled barreled guns.

Riot gun has long been a synonym for a shotgun, especially a short-barrelled shotgun. During the 19th and early 20th century, these were used to disperse rioters and revolutionaries. The wide spray of the shot ensured a large group would be hit, but the light shot would ensure more wounds than fatalities. When the ground was paved, police officers would often ricochet the shot off the ground, slowing down the shot and spreading pattern even further. To this day specialized police and defensive shotguns are called riot shotguns. The introduction of rubber bullets and bean bag rounds ended the practice of using shot for the most part, but riot shotguns are still used to fire a variety of less lethal rounds for riot control.

A sawed-off shotgun (or "sawn-off") refers to a shotgun whose barrel has been shortened, leaving it more maneuverable, easier to use at short range and more readily concealed. Many countries establish a legal minimum barrel length that precludes easy concealment (this length is in the U.S.). The sawed-off shotgun is sometimes known as a "Lupara" (in Italian a generic reference to the word "lupo" ("wolf")) in Southern Italy and Sicily.

Coach guns are similar to sawn-off shotguns, except they are manufactured with an 46 cm (18") barrel and are legal for civilian ownership in some jurisdictions. Coach guns are also more commonly associated with the American Old West or Australian Colonial period, and often used for hunting in bush, scrub, or marshland where a longer barrel would be unwieldy or impractical.

A backpacker shotgun has a short barrel and either a full-size stock or pistol grip, depending on legislation in intended markets. The overall length of these weapons is frequently less than, with some measuring up at less than. These weapons are typically break-action .410 "gauge" (caliber), single-barrel designs with no magazine and no automatic ejection capability. They typically employ a cylinder bore and sometimes are available in modified choke as well.

Backpacker shotguns are popular for "home defense" purposes and as "survival" weapons. Other examples include a variety of .410 / rifle "survival" guns manufactured in over/under designs. In the drilling arrangement, a rimfire or centrefire rifle barrel is located beneath the barrel of a .410 gauge shotgun. Generally, there is one manually cocked external hammer and an external selection lever to select which caliber of cartridge to fire. A notable example is the Springfield Armory M6 Scout, a .410 / .22 issued to United States Air Force personnel as a "survival" gun in the event of a forced landing or accident in a wilderness area. Variants have been used by Israeli, Canadian, and American armed forces. Shotgun-rifle combination guns with two, three, and occasionally even four barrels are available from a number of makers, primarily European. These provided flexibility, enabling the hunter to effectively shoot at flushing birds or more distant small mammals while only carrying one gun.

Ammunition
The extremely large caliber of shotgun shells has led to a wide variety of different ammunition.
 * Shotshells  are the most commonly used round, filled with lead or lead substitute pellets.

Of this general class, the most common subset is birdshot, which uses a large number (from dozens to hundreds) of small pellets, meant to create a wide "kill spread" to hunt birds in flight. Shot shells are described by the size and number of the pellets within, and numbered in reverse order (the smaller the number, the bigger the pellet size, similar to bore gauge). Size nine (#9) shot is the smallest size normally used for hunting and is used on small upland game birds such as dove and quail. Larger sizes are used for hunting larger upland game birds and waterfowl.
 * Buckshot is similar to but larger than birdshot, and was originally designed for hunting larger game, such as deer (hence the name). While the advent of new, more accurate slug technologies is making buckshot less attractive for hunting, it is still the most common choice for police, military, and home defense uses. Like birdshot, buckshot is described by pellet size, with larger numbers indicating smaller shot. From the smallest to the largest, buckshot sizes are: #4, (called "number four"), #1, 0 ("one-aught"), 00 ("double-aught"), 000 ("triple-aught") and 0000 ("four-aught"). A typical round for defensive use would be a 12 gauge length 00 buck shell, which contains 9 pellets roughly 8.4 mm (.33 inch) in diameter, each comparable to a .38 Special bullet in damage potential. New "tactical" buckshot rounds, designed specifically for defensive use, use slightly fewer shot at lower velocity to reduce recoil and increase controllability of the shotgun. There are some shotgun rounds designed specifically for police use that shoot effectively from with a 20" diameter grouping of the balls.
 * Slug rounds are rounds that fire a single solid slug. They are used for hunting large game, and in certain military and law enforcement applications. Modern slugs are moderately accurate, especially when fired from special rifled slug barrels. They are often used in "shotgun-only" hunting zones near inhabited areas, where rifles are prohibited due to their greater range.
 * Sabots are a common type of slug round. While some slugs are exactly that—a 12-gauge metal projectile in a cartridge—a sabot is a smaller but more aerodynamic projectile surrounded by a "shoe" of some other material. This "sabot" jacket seals the barrel, increasing pressure and acceleration, while also inducing spin on the projectile in a rifled barrel. Once the projectile clears the barrel, the sabot material falls away, leaving an unmarked, aerodynamic bullet to continue toward the target. The advantages over a traditional slug are increased shot power, increased bullet velocity due to the lighter-mass bullet, and increased accuracy due to the velocity and the reduction in deformation of the slug itself. Disadvantages versus a traditional slug include lower muzzle momentum due to reduced mass, reduced damage due to smaller bullet diameter, and significantly higher per-unit cost.

Specialty Ammunition
The unique properties of the shotgun, such as large case capacity, large bore, and the lack of rifling, has led to the development of a large variety of specialty shells, ranging from novelties to high tech military rounds.

Hunting, Defensive, & Military

 * Brenneke and Foster type slugs have the same basic configuration as normal slugs, but have increased accuracy. The hollowed rear of the Foster slug improves accuracy by placing more mass in the front of the projectile, therefore inhibiting the "tumble" that normal slugs may generate. The Brenneke slug takes this concept a bit further, with the addition of a wad that stays connected to the projectile after discharge, increasing accuracy. Both slugs are commonly found with fins or rib, which are meant to allow the projectile to safely squeeze down during passage through chokes, but they do not increase stability in flight.
 * Flechette rounds contain aerodynamic darts, typically from 8 to 20 in number. The flechette provide greatly extended range due to their aerodynamic shape, and improved penetration of light armor. American troops during the Vietnam War packed their own flechette shotgun rounds, called beehive rounds, after the similar artillery rounds. However, terminal performance was poor due to the very light weight of the flechettes, and their use was quickly dropped.
 * Frag-12 shotgun rounds are a series of special purpose shotgun grenades, including high explosive blast, fragmentation, and HEAP grenades intended to be fired from any 12-ga shotgun. They are distinguished from regular shotgun rounds by a green hull. It has been proposed as an armament for modern UAVs and is currently being tested for military deployment.
 * Grenade rounds use exploding projectiles to increase long range lethality. These are currently experimental, but the British FRAG-12, which comes in both armor penetrating and fragmentary forms, is under consideration by military forces.

Less Lethal Rounds, For Riot & Animal Control

 * Flexible baton rounds, commonly called bean bags, fire a fabric bag filled with birdshot or a similar loose, dense substance. The "punch" effect of the bag is useful for knocking down targets; the rounds are used by police to subdue violent suspects. The bean bag round is by far the most common less lethal round used. Due to the large surface area of these rounds, they lose velocity rapidly, and must be used at fairly short ranges to be effective, though use at extremely short ranges, under 3m, can result in broken bones or other serious or lethal injuries. The rounds can also fly in a frisbee-like fashion and cut the person or animal being fired at. For this reason, these types of rounds are referred to as less lethal, as opposed to less-than-lethal.
 * Gas shells spray a cone of gas for several meters. These are primarily used by riot police. They normally contain pepper gas or tear gas. Other variations launch a gas-grenade-like projectile.
 * Rock salt shells are hand loaded with coarse rock salt crystals, replacing the standard lead or steel shot. Rock salt shells could be seen as the forerunners of modern less-lethal rounds. In the United States, rock salt shells were and are sometimes still used by rural civilians to defend their property. The brittle salt was unlikely to cause serious injury at long ranges, but would cause painful stinging injuries and served as a warning. British gamekeepers have used rock salt shells to deter poachers. Rather than get into a physical confrontation, they stalk the poachers, making themselves known by a loud shout of "Run!" just before firing, to avoid hitting the now-fleeing subject in the eyes.
 * Rubber slugs or rubber buckshot are similar in principle to the bean bag rounds. Composed of flexible rubber or plastic and fired at low velocities, these rounds are probably the most common choice for riot control.

Taser International announced in 2007 a new 12 gauge eXtended Range Electronic Projectile or XREP, which contains a small electroshock weapon unit in a carrier that can be fired from a standard 12 gauge shotgun. The XREP projectile is fin stabilized, and travels at an initial velocity of 100m/s (300ft/s). Barbs on the front attach the electroshock unit to the target, with a tassel deploying from the rear to widen the circuit. A twenty second burst of electrical energy is delivered to the target. This product is expected to be released to market in 2008. They were used — despite still being subject to testing, in breach of the supplier's license — by Northumbria police in their standoff with Raoul Moat in 2010.
 * Breaching rounds, often called Frangible, Disintegrator, or Hatton rounds, are designed to destroy door locking mechanisms without risking lives. They are constructed of a very brittle substance that transfers most of the energy to the primary target but then fragment into much smaller pieces or dust so as not to injure unseen targets such as hostages or non-combatants that may be standing behind a breached door.
 * Bird bombs are low-powered rounds that fire a firecracker that is fused to explode a short time after firing. They are designed to scare animals, such as birds that congregate on airport runways.
 * Screechers fire a pyrotechnic whistle that emits a loud whistling sound for the duration of its flight. These are also used to scare animals.
 * Blank shells contain only a small amount of powder and no actual load. When fired, the blanks provide the sound and flash of a real load, but with no projectile. These may be used for simulation of gunfire, scaring wildlife, or as power for a launching device such as the Mossberg #50298 marine line launcher.
 * Stinger is a type of shotgun shell which contains 16-00 buck balls made of zytel, and is designed as a non-lethal ammunition ideally used in small spaces.

Novelty & Other
Bolo rounds are made of two or more slugs molded onto steel wire. When fired, the slugs separate, pulling the wire taut creating a flying blade, which could theoretically decapitate people and animals or amputate limbs. However, many active shotgun users consider this to be overstated, and view bolo shells as being less effective than conventional ammunition. Bolo shell rounds are banned in many locations (including the US states of Florida and Illinois) due to concerns about their potential lethality. The round is named in reference to bolas, which use two or more weighted balls on a rope to trap cattle or game.

Dragon's Breath usually refers to a zirconium-based pyrotechnic shotgun round. When fired, a gout of flame erupts from the barrel of the gun (up to 20 ft). The visual effect it produces is impressive, similar to that of a short ranged flamethrower. However, it has few tactical uses, mainly distraction/disorientation.

Flare rounds are sometimes carried by hunters for safety and rescue purposes. They are available in low and high altitude versions. Some brands claim they can reach a height of up to 200m.

Australia
Within Australia, all shotguns manufactured after January 1, 1901 are considered firearms and are subject to registration and licensing. Most shotguns (including break-action, bolt-action and lever-action shotguns) are classed as "Category A" weapons and, as such, are comparatively easy to obtain a licence for, given a legally recognised 'legitimate reason' (compare to the British requirement for 'good reason' for a FAC), such as target shooting or hunting. However, pump-action and semi-automatic shotguns are classed as "Category C" weapons; a licence for this type of firearm is, generally speaking, not available to the average citizen. For more information, see Gun politics in Australia.

Canada
Canada has three classifications of firearms: non-restricted, restricted, and prohibited. Shotguns are found in all three classes.

All non-restricted shotguns must have an overall length of 660mm. Semi-automatic shotguns must also have a barrel length of more than 470mm and have a capacity of 5 shells or less in the magazine to remain non-restricted. All other shotgun action types (pump/slide, break open, lever, bolt) do not have a magazine limit restriction or a minimum barrel length provided the overall length of the firearm remains more than 660 mm and the barrel was produced by an approved manufacturer. Shotgun barrels may only be reduced in length to a minimum of 457mm. Non-restricted shotguns may be possessed with any Possession and Acquisition Licence (PAL) or Possession-Only License (POL) and may be transported throughout the country without special authorization and may be used for hunting certain species at certain times of the year.

Semi-automatic shotguns with a barrel length of less than 470 mm are considered restricted and any shotgun that has been altered so its barrel length is less than 457mm or if its overall length is less than 660mm is considered prohibited. Restricted and prohibited shotguns may be possessed with a PAL or POL than has been endorsed for restricted or prohibited grandfathered firearms. These shotguns require special Authorization to Transport (ATT).

The Canadian Firearms Registry was a government-run registry of all legally owned firearms in Canada. The government provided amnesty from prosecution to shotgun and rifle owners if they fail to register non-restricted shotguns and rifles. The long gun portion of the registry was scrapped in 2011.

UK
In the United Kingdom, a Shotgun Certificate (SGC) is required to possess a "Section 2" shotgun. These cost £50 and can only be denied if the chief of police in the area believes and can prove that the applicant poses a real danger to the public, or if the applicant has been convicted of a crime punishable by imprisonment for a term of three years or more or if the applicant cannot securely store a shotgun (gun clamps, wire locks and locking gun cabinets are considered secure). The round number restrictions apply only to the magazine, not the chamber, so it is legal to have a single-barreled semi-auto or pump-action shotgun that holds three rounds in total, or a shotgun with separate chambers (which would need to also be multi-barrelled). For a shotgun to qualify as a section 2 shotgun, it must meet the following criteria:
 * (a) has a barrel not less than 24 in in length and does not have any barrel with a bore more than 2 in in diameter;
 * (b) either has no magazine or has a non-detachable magazine not capable of holding more than two cartridges;
 * (c) is not a revolver gun.

Prior to a SGC being issued an interview is conducted with the local Firearms Officer, in the past this was a duty undertaken by the local police although more recently this function has been "contracted out" to civilian staff. The officer will check the location and suitability of the gun safe that is to be used for storage and conduct a general interview to establish the reasons behind the applicant requiring a SGC.

An SGC holder can own any number of shotguns meeting these requirements so long as he/she can store them securely. No certificate is required to own shotgun ammunition, but one is required to buy it. There is no restriction on the amount of shotgun ammunition that can be bought or owned. There are also no rules regarding the storage of ammunition.

However, shotgun ammunition which contains fewer than 6 projectiles requires a section 1 Firearms Certificate (FAC). Shotguns with a magazine capacity greater than 2 rounds are also considered to be section 1 firearms and, as such, require an FAC to own. An FAC costs £50 but is much more restrictive than an SGC. The applicant must nominate two referees who are known to the applicant to vouch for his or her character; a new 'variation' is required for each new caliber of gun to be owned; limits are set on how much ammunition a person can own at any one time; and an FAC can be denied if the applicant does not have sufficient 'good reason'. 'Good reason' generally means hunting, collecting, or target shooting - though other reasons may be acceptable, personal defence is not an acceptable reason.

Any pump-action or semi-automatic smooth-bore gun (such as a shotgun) with a barrel length of less than 24 inches or total length of less than 40 inches is considered to be a section 5 firearm, that is, one that is subject to general prohibition, unless it is chambered for .22 caliber rimfire ammunition.

US
In the US, federal law prohibits shotguns from being capable of holding more than three shells including the round in the chamber when used for hunting migratory gamebirds such as doves, ducks, and geese. For other uses, a capacity of any number of shells is generally permitted. Most magazine-fed shotguns come with a removable magazine plug to limit capacity to 2, plus one in the chamber, for hunting migratory gamebirds. Certain states have restrictions on magazine capacity or design features under hunting or assault weapon laws.

Shotguns intended for defensive use have barrels as short as 18 in for private use (the minimum shotgun barrel length allowed by law in the United States without federal registration. Barrel lengths of less than as measured from the breechface to the muzzle when the weapon is in battery, or have an overall length of less than are classified as short barreled shotguns (SBS) under the 1934 National Firearms Act and are regulated. A similar short barreled weapon having a pistol grip may be classified as an AOW or "Any Other Weapon". A shotgun is defined as a weapon (with a buttstock) designed to be fired from the shoulder. The classification varies depending on how the weapon was originally manufactured.

Shotguns used by military, police, and other government agencies are regulated under the National Firearms Act of 1934; however, they are exempt from transfer taxes. These weapons commonly have barrels as short as 12 to 14 in so that they are easier to handle in confined spaces. Non-prohibited private citizens may own short-barreled shotguns by passing extensive background checks (state and local laws may be more restrictive) as well as paying a $200 federal tax and being issued a stamp. Defensive shotguns sometimes have no buttstock or will have a folding stock to reduce overall length even more when required. AOWs transfer with a $5 tax stamp from the BATFE.