12 Gauge

A **shotgun** (also known as a **scattergun** and **peppergun**,[1] 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 5 cm (2.0 in) 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. Militants or insurgents may use shotguns in asymmetric engagements, as shotguns are commonly-owned civilian weapons in many countries. 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

Series of individual 1/1,000,000 second exposures showing shotgun firing shot and wadding separation

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.[2] 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.[2]
 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.[3]

### Sporting

Vincent Hancock in the men's skeet finals at the 2008 Summer Olympics

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 popular for bird hunting
 (called "game-shooting" in the UK, where "hunting" refers to hunting
mammals with a pack of hounds), 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 (110 yd) 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 close - 25m 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.

A Gurkha Contingent trooper in Singapore armed with a folding stock pump shotgun

### 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.[*citation needed*] This is largely a myth, as the spread of buckshot at 25 feet averages 8 inches,[*citation needed*] which is still very capable of missing a target.[*citation needed*] 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

See also: Combat shotgun

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 in Iraq, being popular with soldiers 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 and personal defense

Shotguns are a 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.[4]

## Types

A U.S. Marine fires a Benelli M4 shotgun during training in Arta, Djibouti, December 23, 2006.

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." It is even more broadly defined in English law: "a smooth bore
 gun not being an air gun" (s.1(3)(a) Firearms Act 1968).

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 18 inches
(460 mm) in the U.S. and 24 inches in the UK). 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 90 cm (35 in),
with some measuring up at less than 63 cm (25 in). 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.

## History

Confederate cavalryman

Most early firearms, such as the blunderbuss, arquebus, and musket
 had large diameter, smoothbore barrels, and could fire shot as well as
solid balls. A firearm intended for use in wing shooting of birds was
known as a **fowling piece**. The 1728 *Cyclopaedia* defines a *fowling piece* as:

*Fowling Piece, a portable Fire Arm for the shooting of Birds. See Fire Arm.*
*Of Fowling Pieces, those are reputed the best, which have the longest Barrel, vis. from 51⁄2*

```
foot to 6; with an indifferent Bore, under Harquebus: Tho' for

```

different Occasions they shou'd be of different Sorts, and Sizes. But in
 all, 'tis essential the Barrel be well polish'd and smooth within; and
the Bore all of a Bigness, from one End to another...*[5]*
For example, the Brown Bess musket,
 in service with the British army from 1722 to 1838, had a 19 mm
(.75 inch) smoothbore barrel, roughly the same as a 10 gauge shotgun,
and was 157 cm (62 in) long, just short of the above recommended 168 cm
(51⁄2 feet). On the other hand, records from the Plymouth colony show a maximum length of 137 cm (41⁄2 feet) for fowling pieces,[6] shorter than the typical musket.

Shot was also used in warfare; the buck and ball
 loading, combining a musket ball with three or six buckshot, was used
throughout the history of the smoothbore musket. The first recorded use
of the term *shotgun* was in 1776 in Kentucky. It was noted as part of the "frontier language of the West" by James Fenimore Cooper.

With the adoption of smaller bores and rifled barrels, the shotgun
began to emerge as a separate entity. Shotguns have long been the
preferred method for sport hunting of birds, and the largest shotguns,
the punt guns, were used for commercial hunting. The double-barreled shotgun has changed little since the development of the boxlock
 action in 1875. Modern innovations such as interchangeable chokes and
subgauge inserts make the double-barreled shotgun the shotgun of choice
in skeet, trap shooting, and sporting clays, as well as with many hunters.

As wing shooting has been a prestige sport, specialty gunsmiths such as Krieghoff or Perazzi
 have produced fancy double-barrel guns for wealthy European and
American hunters. These weapons can cost US$5,000 or more; some
elaborately decorated presentation guns have sold for up to US$100,000.[7]

During its long history, the shotgun has been favored by bird hunters, guards, and law enforcement officials. The shotgun has fallen in and out of favor with military
 forces several times in its long history. Shotguns and similar weapons
are simpler than long-range rifles, and were developed earlier. The
development of more accurate and deadlier long-range rifles minimized
the usefulness of the shotgun on the open battlefields of European wars.
 But armies have "rediscovered" the shotgun for specialty uses many
times.

### 19th century

During the 19th century, shotguns were mainly employed by cavalry units. Both sides of the American Civil War employed shotguns. U.S. cavalry used the shotgun extensively during the Indian Wars
 in the latter half of the 19th century. Mounted units favored the
shotgun for its moving target effectiveness, and devastating close-range
 firepower. The shotgun was also favored by citizen militias and similar
 groups.

With the exception of cavalry units, the shotgun saw less and less
use throughout the 19th century on the battlefield. As a defense weapon
it remained popular with guards and lawmen, however, and the shotgun
became one of many symbols of the American Old West. Lawman Cody Lyons killed two men with a shotgun; his friend Doc Holliday's
 only confirmed kill was with a shotgun. The weapon both these men used
was the short-barreled version favored by private strongbox guards on
stages and trains. These guards, called express messengers, became known
 as shotgun messengers,
 since they rode with the weapon (loaded with buckshot) for defense
against bandits. Passenger carriages carrying a strongbox usually had at
 least one private guard armed with a shotgun riding in front of the
coach, next to the driver. This practice has survived in American slang; the term "riding shotgun"
 is used for the passenger who sits in the front passenger seat. The
shotgun was a popular weapon for personal protection in the American Old West, requiring less skill on the part of the user than a revolver.

### Hammerless shotguns

The origins of the hammerless shotgun are European but otherwise
obscure. The earliest breechloading shotguns originated in France and
Belgium in the early 19th century (see also the history of the Pinfire)
 and a number of them such as those by Robert and Chateauvillard from
the 1830s and 1840s did not use hammers. In fact during these decades a
wide variety of ingenious weapons, including rifles, adopted what is now
 often known as a 'needle-fire' method of igniting the charge, where a
firing pin or a longer sharper needle provided the necessary impact. The
 most widely used British hammerless needle-fire shotgun was the unusual
 hinged-chamber fixed-barrel breech-loader by Joseph Needham, produced
from the 1850s. By the 1860s hammerless guns were increasingly used in
Europe both in war and sport although hammer guns were still very much
in the majority. The first significant encroachment on hammer guns was a
 hammerless patent which could be used with a conventional side-lock.
This was British gunmaker T Murcott's 1871 action nicknamed the
'mousetrap' on account of its loud snap action. However, the most
successful hammerless innovation of the 1870s was Anson and Deeley's boxlock
 patent of 1875. This simple but ingenious design only used four moving
parts allowing the production of cheaper and reliable shotguns.

Daniel Myron LeFever
 is credited with the invention of the American hammerless shotgun.
Working for Barber & LeFever in Syracuse, N.Y. he introduced his
first hammerless shotgun in 1878. This gun was cocked with external
cocking levers on the side of the breech. He went on to patent the first
 truly automatic hammerless shotgun in 1883. This gun automatically
cocked itself when the breech was closed. He later developed the
mechanism to automatically eject the shells when the breech was opened.

### John Moses Browning

One of the men most responsible for the modern development of the shotgun was prolific gun designer John Browning. While working for Winchester Firearms, Browning revolutionized shotgun design. In 1887, Browning introduced the Model 1887 Lever Action Repeating Shotgun,
 which loaded a fresh cartridge from its internal magazine by the
operation of the action lever. Before this time most shotguns were the 'break open' type.

This development was greatly overshadowed by two further innovations
he introduced at the end of the 19th century. In 1893, Browning produced
 the Model 1893 Pump Action Shotgun, introducing the now familiar pump
action to the market. And in 1900, he patented the Browning Auto-5, the world's first semi-automatic shotgun. The Browning Auto-5 remained in production until 1998.

### World wars

The decline in military use of shotguns reversed in World War I. American forces under General Pershing employed 12-gauge pump action shotguns when they were deployed to the Western front in 1917. These shotguns were fitted with bayonets
 and a heat shield so the barrel could be gripped while the bayonet was
deployed. Shotguns fitted in this fashion became known as *trench guns* by the United States Army. Those without such modifications were known as *riot guns*. After World War I, the United States military began referring to all shotguns as *riot guns*.

Due to the cramped conditions of trench warfare, the American shotguns were extremely effective. Germany even filed an official diplomatic protest against their use, alleging they violated the laws of warfare. The judge advocate general
 reviewed the protest, and it was rejected because the Germans protested
 use of lead shot (which would have been illegal) but military shot was
plated. This is the only occasion the legality of the shotgun's use in
warfare has been questioned.[8]

A United States Marine carrying a Winchester M97 shotgun during World War II

During World War II,
 the shotgun was not heavily used in the war in Europe by official
military forces. However, the shotgun was a favorite weapon of
Allied-supported partisans, such as the French Resistance. By contrast, in the Pacific theater, thick jungles and heavily fortified positions made the shotgun a favorite weapon of the United States Marines.
 Marines tended to use pump shotguns, since the pump action was less
likely to jam in the humid and dirty conditions of the Pacific campaign.
 Similarly, the United States Navy used pump shotguns to guard ships when in port in Chinese harbors (e.g., Shanghai). The United States Army Air Forces
 also used pump shotguns to guard bombers and other aircraft against
saboteurs when parked on airbases across the Pacific and on the West
Coast of the United States. Pump and semi-automatic shotguns were used
in marksmanship training, particularly for bomber gunners. The most
common pump shotguns used for these duties were the 12 gauge Winchester Model 97 and Model 12. The break-open action, single barrel shotgun was used by the British Home Guard
 and U.S. home security forces. Notably, industrial centers (such as the
 Gopher State Steel Works) were guarded by National Guard soldiers with Winchester Model 37 12 gauge shotguns.

### Late 20th century to present

Since the end of World War II, the shotgun has remained a specialty
weapon for modern armies. It has been deployed for specialized tasks
where its strengths were put to particularly good use. It was used to
defend machine gun emplacements during the Korean War, American and French jungle patrols used shotguns during the Vietnam War, and shotguns saw extensive use as door breaching and close quarter weapons in the early stages of the Iraq War, and saw limited use in tank crews.[9] Many modern navies
 make extensive use of shotguns by personnel engaged in boarding hostile
 ships, as any shots fired will almost certainly be over a short range.
Nonetheless, shotguns are far less common in military use than rifles,
carbines, submachineguns, or pistols.

On the other hand, the shotgun has become a standard in law
enforcement use. A variety of specialty less-lethal or non-lethal
ammunitions, such as tear gas shells, bean bags, flares, explosive sonic
 stun rounds, and rubber projectiles, all packaged into 12 gauge shotgun
 shells, are produced specifically for the law enforcement market.
Recently, Taser International introduced a self-contained electronic weapon which is fired from a standard 12 gauge shotgun.[10]

The shotgun remains a standard firearm for hunting throughout the
world for all sorts of game from birds and small game to large game such
 as deer. The versatility of the shotgun as a hunting weapon has
steadily increased as slug rounds and more advanced rifled barrels have
given shotguns longer range and higher killing power. The shotgun has
become a ubiquitous firearm in the hunting community.

## Design factors

### Action

Action is the term for the operating mechanism of a gun. There are
many types of shotguns, typically categorized by the number of barrels
or the way the gun is reloaded.

A view of the break-action of a typical double-barrelled shotgun, shown with the action open

#### Break-action

For most of the history of the shotgun, the break-action breech loading double
 was the most common type, typically divided into two subtypes: the
traditional "side by side" shotgun features two barrels mounted one
beside the other (as the name suggests), whereas the "over and under"
shotgun has the two barrels mounted one on top of the other. Side by
side shotguns were traditionally used for hunting and other sporting
pursuits (early long barreled side-by side shotguns were known as
"fowling pieces" for their use hunting ducks and other birds), whereas
over and under shotguns are more commonly associated with sporting use
(such as clay pigeon and skeet shooting). Both types of double-barrel
shotgun are used for hunting and sporting use, with the individual
configuration largely being a matter of personal preference.

Another, less commonly encountered type of break-action shotgun is the combination gun,
 which is an over and under design with one shotgun barrel and one rifle
 barrel (more often rifle on top, but rifle on bottom was not uncommon).
 There is also a class of break action guns called *drillings*,
which contain three barrels, usually two shotgun barrels of the same
gauge and a rifle barrel, though the only common theme is that at least
one barrel be a shotgun barrel. The most common arrangement was
essentially a side by side shotgun with the rifle barrel below and
centered. Usually a drilling containing more than one rifle barrel would
 have both rifle barrels in the same caliber, but examples do exist with different caliber barrels, usually a .22 long rifle and a centerfire cartridge. Although very rare, drillings with three and even four (a *vierling*) shotgun barrels were made.

#### Pump-action

A Winchester M1897, one of the first successful pump-action shotgun designs

In pump-action shotguns, a sliding forearm handle (the *pump*)
 works the action, extracting the spent shell and inserting a new one
while cocking the hammer or striker as the pump is worked. A pump gun is
 typically fed from a tubular magazine underneath the barrel, which also
 serves as a guide for the pump. The rounds are fed in one by one
through a port in the receiver, where they are lifted by a lever called
the *elevator* and pushed forward into the chamber by the bolt. A
pair of latches at the rear of the magazine hold the rounds in place and
 facilitate feeding of one shell at a time. If it is desired to load the
 gun fully, a round may be loaded through the ejection port directly
into the chamber, or cycled from the magazine, which is then topped off
with another round. Well-known examples include the Winchester Model 1897, Remington 870 and Mossberg 500/590.

Pump-action shotguns are common hunting, fowling and sporting
shotguns. Hunting models generally have a barrel between 600 and 700 mm
(24"-28"). Tube-fed models designed for hunting often come with a dowel
rod or other stop that is inserted into the magazine and reduces the
capacity of the gun to three shells (two in the magazine and one
chambered) as is mandated by U.S. federal law when hunting migratory
birds. They can also easily be used with an empty magazine as a
single-shot weapon, by simply dropping the next round to be fired into
the open ejection port after the spent round is ejected. For this
reason, pump-actions are commonly used to teach novice shooters under
supervision, as the trainer can load each round more quickly than with a
 break-action, while unlike a break-action the student can maintain his
grip on the gun and concentrate on proper handling and firing of the
weapon.

Pump action shotguns with shorter barrels and little or no barrel
choke are highly popular for use in home defense, military and law
enforcement, and are commonly known as riot guns.
 The minimum barrel length for shotguns in most of the U.S. is 18 inches
 (460 mm), and this barrel length (sometimes 18.5–20 in (470–510 mm) to
increase magazine capacity and/or ensure the gun is legal regardless of
measuring differences[11])
 is the primary choice for riot shotguns. The shorter barrel makes the
weapon easier to maneuver around corners and in tight spaces, though
slightly longer barrels are sometimes used outdoors for a tighter spread
 pattern or increased accuracy of slug projectiles. Home-defense and law
 enforcement shotguns are usually chambered for 12-gauge shells,
providing maximum shot power and the use of a variety of projectiles
such as buckshot, rubber, sandbag and slug shells, but 20-gauge (common
in bird-hunting shotguns) or .410 (common in youth-size shotguns) are
also available in defense-type shotgun models allowing easier use by
novice shooters.

A riot shotgun has many advantages over a handgun or rifle. Compared to "defense-caliber" handguns (chambered for 9mm Parabellum, .38 Special, .357 Magnum, .40 S&W, .45 ACP and similar), a shotgun has far more power and damage potential (up to 10 times the muzzle energy of a .45 ACP cartridge), allowing a "one-shot stop"
 that is more difficult to achieve with typical handgun loads. Compared
to a rifle, riot shotguns are easier to maneuver due to the shorter
barrel, still provide better damage potential at indoor distances
(generally 3–5 meters/yards), and reduce the risk of "overpenetration";
that is, the bullet or shot passing completely through the target and
continuing beyond, which poses a risk to those behind the target through
 walls. The wide spread of the shot reduces the importance of shot
placement compared to a single projectile, which increases the
effectiveness of "point shooting" - rapidly aiming simply by pointing
the weapon in the direction of the target. This allows easy, fast use by
 novices.

#### Lever-action

A modern reproduction of the Winchester M1887 lever-action shotgun

Early attempts at repeating shotguns invariably centred around either bolt-or lever-action
 designs, drawing inspiration from contemporary repeating rifles, with
the earliest successful repeating shotgun being the lever-action Winchester M1887, designed by John Browning at the behest of the Winchester Repeating Arms Company.

Lever shotguns, while less common, were popular in the late 19th
century with the Winchester Model 1887 and Model 1901 being prime
examples. Initially very popular, demand waned after the introduction of
 pump-action shotguns around the start of the 20th century, and
production was eventually discontinued in 1920.

One major issue with lever-actions (and to a lesser extent
pump-actions) was that early shotgun shells were often made of paper or
similar fragile materials (modern hulls are plastic or metal). As a
result, the loading of shells, or working of the action of the shotgun,
could often result in cartridges getting crushed and becoming unusable,
or even damaging the gun.

Lever shotguns have seen a return to the gun market in recent years,
however, with Winchester producing the Model 9410 (chambering the .410
gauge shotgun shell and using the action of the Winchester Model 94
series lever-action rifle, hence the name), and a handful of other
firearm manufacturers (primarily Norinco of China and ADI Ltd. of Australia) producing versions of the Winchester Model 1887/1901 designed for modern 12-gauge smokeless
 shotshells with more durable plastic casings. There has been a notable
uptick in lever-action shotgun sales in Australia since 1997, when
pump-actions were effectively outlawed.

#### Semi-automatic

A Browning A-5 semi-automatic shotgun

Gas, inertia, or recoil operated actions are other popular methods of
 increasing the rate of fire of a shotgun; these are generally referred
to as autoloaders
 or semi-automatics. Instead of having the action manually operated by a
 pump or lever, the action automatically cycles each time the shotgun is
 fired, ejecting the spent shell and reloading a fresh one into the
chamber. The first successful semi-automatic shotgun was John Browning's Auto-5, first produced by Fabrique Nationale beginning in 1902. Other well-known examples include the Remington 1100, Benelli M1, and Saiga-12.

Some, such as the Franchi SPAS-12 and Benelli M3,
 are capable of switching between semi-automatic and pump action. These
are popular for two reasons; first, some jurisdictions forbid the use of
 semi-automatic actions for hunting, and second, lower-powered rounds,
like "reduced-recoil" buckshot shells and many less-lethal cartridges, have insufficient power to reliably cycle a semi-automatic shotgun.

#### Bolt-action

Bolt-action
 shotguns, while uncommon, do exist. One of the best-known examples is a
 12 gauge manufactured by Mossberg featuring a 3-round magazine,
marketed in Australia just after changes to the gun laws in 1997 heavily
 restricted the ownership and use of pump-action and semi-automatic
shotguns. They were not a huge success, as they were somewhat slow and
awkward to operate, and the rate of fire was noticeably slower (on
average) than a double-barrelled gun. The Ishapore Arsenal in India also manufactured a single-shot .410 bore shotgun based on the SMLE Mk III\*
 rifle. The Russian Berdana shotgun was effectively a single-shot
bolt-action rifle that became obsolete, and was subsequently modified to
 chamber 16 gauge shotgun shells for civilian sale. The U.S. military M26
 is also a bolt-action weapon. Bolt-action shotguns have also been used
in the "goose gun" application, intended to kill birds such as geese
 at greater range. Typically, goose guns have long barrels (up to
36 inches), and small bolt-fed magazines. Bolt-action shotguns are also
used in conjunction with slug shells for the maximum possible accuracy
from a shotgun.[12]

#### Other

In addition to the commonly encountered shotgun actions already listed, there are also shotguns based on the Martini-Henry rifle design, originally designed by British arms maker W.W. Greener.

Some of the more interesting advances in shotgun technology include the versatile NeoStead 2000 and fully automatics such as the Pancor Jackhammer or Auto-Assault 12.

In 1925, Rodolfo Cosmi produced the first working hybrid prototype
semi-automatic shotgun, which had an 8-round magazine located in the
stock. While it reloaded automatically after each shot like a
semi-automatic, it had a break-action to load the first shell. This
design has only been repeated once, by Beretta with their UGB25
automatic shotgun. The user loads the first shell by breaking the gun in
 the manner of a break-action shotgun, then closes it and inserts the
second shell into a clip on the gun's right side. The spent hulls are
ejected downwards. The guns combine the advantages of the break action
(they can be proven to be safe by breaking open, there are no flying
hulls) with those of the semi-automatic (low recoil, low barrel axis
position hence low muzzle flip).

### Gauge

A United States Army soldier armed with a Mossberg 500 shotgun

Main article: Gauge (bore diameter)

The caliber of shotguns is measured in terms of *gauge* (U.S.) or *bore* (U.K.).
 The gauge number is determined by the weight, in fractions of a pound,
of a solid sphere of lead with a diameter equal to the inside diameter
of the barrel. So, a 10 gauge shotgun nominally should have an inside
diameter equal to that of a sphere made from one-tenth of a pound of
lead. By far the most common gauges are 12 (0.729 in, 18.5 mm diameter)
and 20 (0.614 in, 15.6 mm), although .410 (= 67), 32, 28, 24, 16, and 10
 (19.7 mm) gauge also exist. Ammunition manufacturer CCI produces 9 mm
(.355 in.) and several other popular pistol calibers up to .45 ACP as
well as .22 (5.5 mm) for firing from handguns. These are commonly called
 snake shot cartridges. rimfire caliber.[13] Larger gauges, too powerful to shoulder, have been built, but were generally affixed to small boats and referred to as punt guns. These were used for commercial waterfowl hunting, to kill large numbers of birds resting on the water. Although relatively rare, single and double derringers
 have also been produced that are capable of firing either .45 (Long)
Colt or .410 shotgun shells from the same chamber; they are commonly
known as "snake guns", and are popular among some outdoorsmen in the
South and Southwest regions of the United States. There are also some
revolvers, such as the Taurus Judge,
 that are capable of shooting the .45LC/.410 rounds; but as with
derringers, these are handguns that shoot .410 shotgun shells, and are
not necessarily considered shotguns.

The .410 bore
 (10.4 mm) is unusual, being measured in inches, and would be
approximately 67 "real" gauge, though its short hull versions are
nominally called 36 gauge in Europe. It uses a relatively small charge
of shot. It is used for hunting and for skeet. Because of its very light
 recoil (approx 10 N), it is often used as a beginner's gun. However,
the small charge and typically tight choke make it more difficult to hit
 targets. It is also frequently used by expert shooters because of the
difficulty, especially in expensive side by side and over/under models
for hunting small bird game such as quail and doves.[14]
 Inexpensive bolt-action .410 shotguns are a very common first hunting
shotgun among young pre-teen hunters, as they are used mostly for
hunting squirrels, while additionally teaching bolt-action manipulation
skills that will transfer easily later to adult-sized hunting rifles.
Most of these young hunters move up to a 20-gauge
 within a few years, and to 12 gauge shotguns and full-size hunting
rifles by their late teens. Still, many who are particularly
recoil-averse choose to stay with 20-gauge shotguns all their adult
life, as it is a suitable gauge for many popular hunting uses.

A recent innovation is the back-boring of barrels, in which the
barrels are bored out slightly larger than their actual gauge. This
reduces the compression forces on the shot when it transitions from the
chamber to the barrel. This leads to a slight reduction in perceived
recoil, and an improvement in shot pattern due to reduced deformation of
 the shot.

### Shot

U.S. Marines fire their shotguns

Most shotguns are used to fire "a number of ball shot", in addition
to slugs and sabots. The ball shot or pellets is for the most part made
of lead but this has been partially replaced by bismuth, steel,
tungsten-iron, tungsten-nickel-iron and even tungsten polymer loads.
Non-toxic loads are required by Federal law for waterfowl hunting
 in the US, as the shot may be ingested by the waterfowl, which some
authorities believe can lead to health problems due to the lead
exposure. Shot is termed either birdshot or buckshot
 depending on the shot size. Informally, birdshot pellets have a
diameter smaller than 5 mm (0.20 in) and buckshot are larger than that.
Pellet size is indicated by a number; for bird shot this ranges from the
 smallest 12 (1.2 mm, 0.05 in) to 2 (3.8 mm, 0.15 in) and then BB
(4.6 mm, 0.18 in).[15]

For buckshot, the numbers usually start at 4 (6.1 mm, 0.24 in) and go
 down to 1, 0, 00 ("double aught"), 000, and finally 0000 (9.7 mm, .38
in). A different informal distinction is that "bird shot" pellets are
small enough that they can be measured into the cartridge by weight, and
 simply poured in, whereas "buckshot" pellets are so large they must be
stacked inside the cartridge in a fixed geometric arrangement in order
to fit. The diameter in hundredths of an inch of bird shot sizes from #9
 to #1 can be obtained by subtracting the shot size from 17. Thus, #4
bird shot is 17 - 4 = 13 = 0.13 inches (3.3 mm) in diameter. Different
terminology is used outside the United States. In England and Australia, for example, 00 buckshot cartridges are commonly referred to as "S.G." (small game) cartridges.

### Pattern and choke

Shot, small and round and delivered without spin, is ballistically
inefficient. As the shot leaves the barrel it begins to disperse in the
air. The resulting cloud of pellets is known as the shot pattern, or shotgun shot spread.
 The ideal pattern would be a circle with an even distribution of shot
throughout, with a density sufficient to ensure enough pellets will
intersect the target to achieve the desired result, such as a kill when
hunting or a break when shooting clay targets. In reality the pattern is
 closer to a Gaussian,
 or normal distribution, with a higher density in the center that tapers
 off at the edges. Patterns are usually measured by firing at a 30
inches (76 cm) diameter circle on a large sheet of paper placed at
varying distances. The hits inside the circle are counted, and compared
to the total number of pellets, and the density of the pattern inside
the circle is examined. An "ideal" pattern would put nearly 100% of the
pellets in the circle and would have no voids—any region where a target
silhouette will fit and not cover 3 or more holes is considered a
potential problem.

A constriction in the end of the barrel known as the choke
 is used to tailor the pattern for different purposes. Chokes may either
 be formed as part of the barrel at the time of manufacture, by
squeezing the end of the bore down over a mandrel,
 or by threading the barrel and screwing in an interchangeable choke
tube. The choke typically consists of a conical section that smoothly
tapers from the bore diameter down to the choke diameter, followed by a
cylindrical section of the choke diameter. Briley Manufacturing, a maker
 of interchangeable shotgun chokes, uses a conical portion about 3 times
 the bore diameter in length, so the shot is gradually squeezed down
with minimal deformation. The cylindrical section is shorter, usually
0.6 to 0.75 inches (15 to 19 millimetres). The use of interchangeable
chokes has made it easy to tune the performance of a given combination
of shotgun and shotshell to achieve the desired performance.

The choke should be tailored to the range and size of the targets. A
skeet shooter shooting at close targets might use 127 micrometres
(0.005 inches) of constriction to produce a 76 cm (30 in) diameter
pattern at a distance of 19 m (21 yd). A trap
 shooter shooting at distant targets might use 762 micrometres
(0.030 inches) of constriction to produce a 76 cm (30 in) diameter
pattern at 37 m (40 yd). Special chokes for turkey hunting, which
requires long range shots at the small head and neck of the bird, can go
 as high as 1500 micrometres (0.060 inches). The use of too much choke
and a small pattern increases the difficulty of hitting the target,
whereas the use of too little choke produces large patterns with
insufficient pellet density to reliably break targets or kill game.
"Cylinder barrels" have no constriction. See also: Slug barrel

Other specialized choke tubes exist as well. Some turkey hunting
tubes have constrictions greater than "Super Full", or additional
features like porting to reduce recoil, or "straight rifling" that is
designed to stop any spin that the shot column might acquire when
traveling down the barrel. These tubes are often extended tubes, meaning
 they project beyond the end of the bore, giving more room for things
like a longer conical section. Shot spreaders or diffusion chokes work
opposite of normal chokes—they are designed to spread the shot more than
 a cylinder bore, generating wider patterns for very short range use. A
number of recent spreader chokes, such as the Briley "Diffusion" line,
actually use rifling in the choke to spin the shot slightly, creating a
wider spread. The Briley Diffusion uses a 1 in 36 cm twist, as does the
FABARM Lion Paradox shotgun.

Oval chokes, which are designed to provide a shot pattern wider than it is tall, are sometimes found on combat shotguns, primarily those of the Vietnam War era. They were available for aftermarket addition in the 1970s from companies like A & W Engineering.[16] Military versions of the Ithaca 37 with *duckbill*
 choke were used in limited numbers during the Vietnam War by US Navy
Seals. It arguably increased effectiveness in close range engagements
against multiple targets. Two major disadvantages plagued the system.
One was erratic patterning. The second was that the shot would spread
too quickly providing a limited effective zone.

Offset chokes, where the pattern is intentionally slightly off of
center, are used to change the point of impact. For instance, an offset
choke can be used to make a double barrelled shotgun with poorly aligned
 barrels hit the same spot with both barrels.

### Barrel length

Shotguns generally have longer barrels than modern rifles. Unlike
rifles, however, the long shotgun barrel is not for ballistic purposes;
shotgun shells use small powder charges in large diameter bores, and
this leads to very low muzzle pressures (see internal ballistics)
 and very little velocity change with increasing barrel length.
According to Remington, modern powder in a shotgun burns completely in
25 (9.8425 in) to 36 (14.173 in) cm barrels.

Since shotguns are generally used for shooting at small, fast moving targets, it is important to *lead*
 the target by firing slightly ahead of the target, so that when the
shot reaches the range of the target, the target will have moved into
the pattern. On uphill shooting, this means to shoot *above* the target. Conversely, on downhill shooting, this means to shoot *below*
 the target, which is somewhat counterintuitive for many beginning
hunters. Of course, depending on the barrel length, the amount of *lead* employed will vary for different barrel lengths, and must be learned by experience.

Shotguns made for close ranges, where the angular speed of the
targets is great (such as skeet or upland bird hunting), tend to have
shorter barrels, around 24 to 28 inches (610 to 710 millimetres).
Shotguns for longer range shooting, where angular speeds are small (trap
 shooting; quail, pheasant, and waterfowl hunting), tend to have longer
barrels, 28 to 36 inches (910 mm). The longer barrels have more angular momentum,
 and will therefore swing more slowly but more steadily. The short, low
angular momentum barrels swing faster, but are less steady. These
lengths are for pump or semi-auto shotguns; break open guns have shorter
 overall lengths for the same barrel length, and so will use longer
barrels. The break open design saves between 9 and 15 cm (3.5 and
5.9 in) in overall length, but in most cases pays for this by having two
 barrels, which adds weight at the muzzle, and so usually only adds a
couple of centimetres. Barrels for shotguns have been getting longer as
modern steels and production methods make the barrels stronger and
lighter; a longer, lighter barrel gives the same inertia for less
overall weight.

Shotguns for use against larger, slower targets generally have even
shorter barrels. Small game shotguns, for hunting game like rabbits and
squirrels, or shotguns for use with buckshot for deer, are often 56 to
61 cm (22 to 24 in).

Shotguns intended for all-round hunting are a compromise, of course,
but a 72 to 74 cm (28 to 29 in) barrel pump-action 12-gauge shotgun with
 a modified choke can serve admirably for use as one gun intended for
general all-round hunting of small-game such as quails, rabbits,
pheasants, doves, and squirrels in semi-open wooded or farmland areas in
 many parts of the eastern US (Kentucky, Indiana, Tennessee) where dense
 brush is less of a hindrance and the ability to have more reach is
important. For hunting in dense brush, shorter barrel lengths are often
preferred when hunting the same types of game.

## Ammunition

Main article: Shotgun shell

Loading 12-gauge shells

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 2 3⁄4 inches (7.0 cm) 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 50 yards (46 m) 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, and 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.

**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.[17]

#### Less-lethal rounds, for riot and animal control

Two rounds of Fiocchi 12 gauge rubber buckshot

**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 3 m (9.8 ft), 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.[18]

**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 100 m/s (300 ft/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.[19] 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.[20] 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.[20] 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.[20] 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.[21]

**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 and 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[22] and Illinois[23]) 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 200 m (660 ft).

## Legal issues

A homemade Lupara

Globally, shotguns are generally not as heavily regulated as rifles
or handguns, likely because they lack the range of rifles and are not
easily concealable as handguns are; thus, they are perceived as a lesser
 threat by legislative authorities. The one exception is a sawed-off shotgun, especially a Lupara, as it is more easily concealed than a normal shotgun.

### 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

A RCMP officer in 2010 armed with a shotgun outfitted to fire beanbag rounds

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 660 mm
(26 in). Semi-automatic shotguns must also have a barrel length of more
than 469.9 mm (18.50 in) 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 (26 in) and the barrel was produced
 by an approved manufacturer. Shotgun barrels may only be reduced in
length to a minimum of 457 mm (18.0 in). 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 469.9 mm
(18.50 in) are considered restricted and any shotgun that has been
altered so its barrel length is less than 457 mm (18.0 in) or if its
overall length is less than 660 mm (26 in) is considered prohibited.[24] 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).[25]

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.[26] The long gun portion of the registry was scrapped in 2011.

See online[27] for an official Canadian list of non-restricted and restricted and prohibited firearms.

### 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 inches (610 mm) in length and does
not have any barrel with a bore more than 2 inches (51 mm) 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.[28]

### US

President Barack Obama skeet shooting with a Browning Citori 525 on the range at Camp David.

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
inches (46 cm) for private use (the minimum shotgun barrel length
allowed by law in the United States without federal registration. Barrel
 lengths of less than 18 inches (46 cm) as measured from the breechface
to the muzzle when the weapon is in battery, or have an overall length
of less than 26 inches (66 cm) 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 inches (30 to 36 centimetres) 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.