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A shotgun shell, shotshell or simply shell is a type of rimmed,
cylindrical A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an infini ...
(straight-walled) cartridges used specifically in
shotgun A shotgun (also known as a scattergun, or historically as a fowling piece) is a long-barreled firearm designed to shoot a straight-walled cartridge known as a shotshell, which usually discharges numerous small pellet-like spherical sub- pr ...
s, and is typically loaded with numerous small, pellet-like spherical sub-
projectile A projectile is an object that is propelled by the application of an external force and then moves freely under the influence of gravity and air resistance. Although any objects in motion through space are projectiles, they are commonly found in ...
s called shot, fired through a
smoothbore A smoothbore weapon is one that has a barrel without rifling. Smoothbores range from handheld firearms to powerful tank guns and large artillery mortars. History Early firearms had smoothly bored barrels that fired projectiles without sign ...
barrel A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids, ...
with a tapered constriction at the muzzle to regulate the extent of scattering. A shell can sometimes also contain only a single large solid projectile known as a
slug Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc. The word ''slug'' is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a smal ...
, fired usually through a
rifled In firearms, rifling is machining helical grooves into the internal (bore) surface of a gun's barrel for the purpose of exerting torque and thus imparting a spin to a projectile around its longitudinal axis during shooting to stabilize the pr ...
slug barrel A slug barrel is a shotgun barrel that is designed primarily to fire slugs instead of shot, and is usually rifled. A shotgun with such a barrel is often called a slug gun. Origins When slugs are fired in a standard, choked barrel, the slug is de ...
. The
hull Hull may refer to: Structures * Chassis, of an armored fighting vehicle * Fuselage, of an aircraft * Hull (botany), the outer covering of seeds * Hull (watercraft), the body or frame of a ship * Submarine hull Mathematics * Affine hull, in affi ...
usually consists of a paper or plastic tube often covered at the base by a metallic head cover which retains a
primer Primer may refer to: Arts, entertainment, and media Films * ''Primer'' (film), a 2004 feature film written and directed by Shane Carruth * ''Primer'' (video), a documentary about the funk band Living Colour Literature * Primer (textbook), a te ...
, and the shot charge is typically contained by a wadding/ sabot inside the case. The
caliber In guns, particularly firearms, caliber (or calibre; sometimes abbreviated as "cal") is the specified nominal internal diameter of the gun barrel bore – regardless of how or where the bore is measured and whether the finished bore match ...
of the shotshell is known as its gauge. The projectiles are traditionally made of lead, but other
metal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typica ...
s such as steel, tungsten and
bismuth Bismuth is a chemical element with the symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental bismuth occurs na ...
are also used due to restrictions on lead, or for performance reasons such as achieving higher shot velocities by reducing the mass of the shot charge. Other unusual projectiles such as saboted flechettes, rubber balls, rock salt and magnesium shards also exist. Slug shells can also be made with specialty
non-lethal Non-lethal weapons, also called nonlethal weapons, less-lethal weapons, less-than-lethal weapons, non-deadly weapons, compliance weapons, or pain-inducing weapons are weapons intended to be less likely to kill a living target than conventional ...
projectiles such as rubber and
bean bag round A bean bag round, also known by its trademarked name flexible baton round, is a type of baton round, fired from a shotgun, and used for less lethal apprehension of suspects. Description The bean bag round consists of a small fabric "pillow" ...
s. Shotguns have an effective range of about with
buckshot A shotgun shell, shotshell or simply shell is a type of rimmed, cylindrical (straight-walled) cartridges used specifically in shotguns, and is typically loaded with numerous small, pellet-like spherical sub-projectiles called shot, fired throu ...
, with
birdshot A shotgun shell, shotshell or simply shell is a type of rimmed, cylindrical (straight-walled) cartridges used specifically in shotguns, and is typically loaded with numerous small, pellet-like spherical sub-projectiles called shot, fired throu ...
, with slugs, and well over with saboted slugs in
rifled barrel In firearms, rifling is machining helical grooves into the internal (bore) surface of a gun's barrel for the purpose of exerting torque and thus imparting a spin to a projectile around its longitudinal axis during shooting to stabilize the p ...
s. Other rounds include: *Ferret rounds: rounds designed to penetrate a thin barrier (e.g. a car door) and release a gas payload. *Bolo rounds: two large lead balls attached by a wire. *Piranha rounds: shells full of sharp tacks. * Dragon's breath rounds: shells full of incendiary chemicals that creates a
fireball Fireball may refer to: Science * Fireball (meteor), a brighter-than-usual meteor * Ball lightning, an atmospheric electrical phenomenon * ''Bassia scoparia'', a plant species Arts and entertainment Films * '' The Fireball'', a 1950 film starring ...
/
flame A flame (from Latin '' flamma'') is the visible, gaseous part of a fire. It is caused by a highly exothermic chemical reaction taking place in a thin zone. When flames are hot enough to have ionized gaseous components of sufficient density they ...
when discharged, and can ignite a flammable target at close range. Most shotgun shells are designed to be fired from a
smoothbore A smoothbore weapon is one that has a barrel without rifling. Smoothbores range from handheld firearms to powerful tank guns and large artillery mortars. History Early firearms had smoothly bored barrels that fired projectiles without sign ...
barrel, but dedicated shotguns with
rifled In firearms, rifling is machining helical grooves into the internal (bore) surface of a gun's barrel for the purpose of exerting torque and thus imparting a spin to a projectile around its longitudinal axis during shooting to stabilize the pr ...
barrels are limited to lead slugs or sabot slugs as "shot" would be spread too wide by the rifling. A rifled barrel will increase the accuracy of sabot slugs, but makes it unsuitable for firing shot, as it imparts a spin to the shot cup, causing the shot cluster to disperse. A rifled slug uses rifling on the slug itself so it can be used in a smoothbore shotgun.


History

Early shotgun shells used brass cases, not unlike pistol and rifle cartridge cases of the same era. These brass shotgun hulls or cases closely resembled large rifle cartridges, in terms of both the head and primer portions of the shotgun shell, as well as in their dimensions. Card wads, made of felt, leather, and cork, as well as paperboard, were all used at various times. Waterglass (Sodium silicate) was commonly used to cement the top overshot wad into these brass shell casings. No roll crimp or fold crimp was used on these early brass cases, although roll crimps were eventually used by some manufacturers to hold the overshot wad in place securely. The primers on these early shotgun shells were identical to pistol primers of the same diameter. Starting in the late 1870s, paper hulls began replacing brass hulls. Paper hulls remained popular for nearly a century, until the early 1960s. These shotgun shells using paper hulls were nearly always roll crimped, although fold crimping also eventually became popular. The primers on these paper hull shotgun shells also changed from the pistol primers used on the early brass shotgun shells to a primer containing both the priming charge and an anvil, unlike rifle and pistol ammunition, making the shotgun shell primer taller. Card wads, made of felt and cork, as well as paperboard, were all used at various times, gradually giving way to plastic over powder wads, with card wads, and, eventually, to all plastic wads. Starting in the early 1960s, plastic hulls started replacing paper hulls for the majority of shotgun shells and by the 1980s, plastic hulls had become universally adopted.


Typical construction

Modern shotgun shells typically consist of a plastic hull, with the base covered in a thin brass or plated steel covering. As noted previously, paper shells used to be common, and are still made, as are solid brass shells. Some companies have produced what appear to be all-plastic shells, although in these there is a small metal ring cast into the rim of the shell to provide strength. Often the more powerful loads will use " high brass" shells, with the brass extended up further along the sides of the shell, while light loads will use "low brass" shells. The brass does not actually provide a significant amount of strength, but the difference in appearance provides shooters with a way to quickly differentiate between high and low powered ammunition. The base of the shell is fairly thick to hold the large shotgun
primer Primer may refer to: Arts, entertainment, and media Films * ''Primer'' (film), a 2004 feature film written and directed by Shane Carruth * ''Primer'' (video), a documentary about the funk band Living Colour Literature * Primer (textbook), a te ...
, which is longer than primers used for rifle and
pistol A pistol is a handgun, more specifically one with the chamber integral to its gun barrel, though in common usage the two terms are often used interchangeably. The English word was introduced in , when early handguns were produced in Europe, a ...
ammunition. Modern smokeless powders are far more efficient than the original
black powder Gunpowder, also commonly known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive. It consists of a mixture of sulfur, carbon (in the form of charcoal) and potassium nitrate (saltpeter). Th ...
used in shotgun shells, so very little space is actually taken by powder; shotguns use small quantities of double base
powders A powder is a dry, bulk solid composed of many very fine particles that may flow freely when shaken or tilted. Powders are a special sub-class of granular materials, although the terms ''powder'' and ''granular'' are sometimes used to distin ...
, equivalent to quick-burning pistol powders, with up to 50% nitroglycerin. After the powder comes the wadding or wad. The primary purpose of a wad is to prevent the shot and powder from mixing, and to provide a seal that prevents gas from blowing through the shot rather than propelling it. The wad design may also encompass a shock absorber and a cup that holds the shot together until it is out of the barrel. A modern wad consists of three parts, the powder wad, the cushion, and the shot cup, which may be separate pieces or be one part. The powder wad acts as the gas seal (known as obturation), and is placed firmly over the powder; it may be a paper or plastic part. The cushion comes next, and it is designed to compress under pressure, to act as a shock absorber and minimize the deformation of the shot; it also serves to take up as much space as is needed between the powder wad and the shot. Cushions are almost universally made of plastic with
crumple zone Crumple zones, crush zones, or crash zones are a structural safety feature used in vehicles, mainly in automobiles, to increase the time over which a change in velocity (and consequently momentum) occurs from the impact during a collision by a ...
s, although for game shooting in areas grazed by farm stock or wildlife biodegradable fiber wads are often preferred. The shot cup is the last part of the shell, and it serves to hold the shot together as it moves down the barrel. Shot cups have slits on the sides so that they peel open after leaving the barrel, allowing the shot to continue on in flight undisturbed. Shot cups, where used, are also almost universally plastic. The shot fills the shot cup (which must be of the correct length to hold the desired quantity of shot), and the shotgun shell is then crimped, or rolled closed.


Sizes


Standard

Shotgun shells are generally measured by " gauge", which is the weight, in fractions of a pound, of a pure lead round ball that is the same diameter as the internal diameter of the barrel; in Britain and some other locations outside the United States the term "bore" is used with the same meaning. This contrasts with rifles and handguns, which are almost always measured in "
caliber In guns, particularly firearms, caliber (or calibre; sometimes abbreviated as "cal") is the specified nominal internal diameter of the gun barrel bore – regardless of how or where the bore is measured and whether the finished bore match ...
", a measurement of the internal diameter of the barrel measured in millimeters or inches and, consequently, is approximately equal to the diameter of the projectile that is fired. For example, a shotgun is called "12-gauge" because a lead sphere that just fits the inside diameter of the barrel weighs . This measurement comes from the time when early cannons were designated in a similar manner—a "12 pounder" would be a cannon that fired a cannonball; inversely, an individual "12-gauge" shot would in fact be a pounder. Thus, a 10-gauge shotgun has a larger-diameter barrel than a 12-gauge shotgun, which has a larger-diameter barrel than a 20-gauge shotgun, and so forth. The most popular shotgun gauge by far is 12-gauge. The larger 10-gauge, once popular for hunting larger birds such as goose and turkey, is in the decline with the advent of longer, "magnum" 12-gauge shells, which offer similar performance. The mid-size 20-gauge is also a very popular chambering for smaller-framed shooters who favor its reduced recoil, those hunting smaller game, and experienced trap and
skeet shooters Skeet may refer to: * Skeet shooting, a discipline of competitive clay pigeon shooting ** ISSF Olympic skeet, a variant used at the Olympic Games People * Skeet Childress (born 1979), American guitar player in the band Look What I Did * Skeet Q ...
who like the additional challenge of hitting their targets with a smaller shot charge. Other less-common, but commercially available gauges are 16 and 28. Several other gauges may be encountered but are considered obsolete. The 4, 8, 24, and 32 gauge guns are collector items. There are also some shotguns measured by diameter, rather than gauge. These are the .410 (10.4mm), .380 (9mm), and .22 (5.5mm); these are correctly called "
.410 bore The .410 bore is one of the smallest caliber of shotgun shell commonly available (along with the 9mm Flobert rimfire cartridge, and the less common .22 rimfire shot shell). A .410 bore shotgun loaded with shot shells is well suited for small g ...
", not ".410-gauge". The .410 bore is the smallest shotgun size which is widely available commercially in the United States. For size comparison purposes, the .410, when measured by gauge, would be around 67- or 68-gauge (it is 67.62-gauge), The .410 is often mistakenly assigned 36-gauge. The 36 gauge was in fact a .360 diameter cartridge which was in length and is now obsolete.


Other calibers

Snake shot (AKA: bird shot, rat shot and dust shot) refers to handgun and rifle cartridges loaded with small lead shot. Snake shot is generally used for shooting at snakes, rodents, birds, and other pest at very close range. The most common snake shot cartridges are
.22 Long Rifle The .22 Long Rifle or simply .22 LR or 22 (metric designation: 5.6×15mmR) is a long-established variety of .22 caliber rimfire ammunition originating from the United States. It is used in a wide range of rifles, pistols, revolvers, smo ...
,
.22 Magnum The .22 Winchester Magnum Rimfire, also called .22 WMR, .22 Magnum, .22 WMRF, .22 MRF, or .22 Mag, is a rimfire cartridge. Originally loaded with a bullet weight of delivering velocities in the range from a rifle barrel, .22 WMR is now loaded ...
,
.38 Special The .38 Special, also commonly known as .38 S&W Special (not to be confused with .38 S&W), .38 Smith & Wesson Special, .38 Spl, .38 Spc, (pronounced "thirty-eight special"), or 9x29mmR is a rimmed, centerfire cartridge designed by Smith & ...
, 9×19mm Luger, .40 Smith & Wesson,
.44 Special The .44 Smith & Wesson Special, also commonly known as .44 S&W Special, .44 Special, .44 Spl, .44 Spc, (pronounced "forty-four special"), or 10.9x29mmR is a smokeless powder center fire metallic revolver cartridge developed by Smith & Wesson in 1 ...
,
.45 ACP The .45 ACP ( Automatic Colt Pistol) or .45 Auto (11.43×23mm) is a rimless straight-walled handgun cartridge designed by John Moses Browning in 1904, for use in his prototype Colt semi-automatic pistol. After successful military trials, it ...
, and
.45 Colt The .45 Colt (11.43×33mmR), is a rimmed, straight-walled, handgun cartridge dating to 1872. It was originally a black-powder revolver round developed for the Colt Single Action Army revolver. This cartridge was adopted by the U.S. Army in 1 ...
. Commonly used by hikers, backpackers and campers, snake shot is ideally suited for use in revolvers and
derringer A derringer is a small handgun that is neither a revolver nor a semi/ fully automatic pistol. It is not to be confused with mini-revolvers or pocket pistols, although some later derringers were manufactured with the pepperbox configuration. ...
s, chambered for
.38 Special The .38 Special, also commonly known as .38 S&W Special (not to be confused with .38 S&W), .38 Smith & Wesson Special, .38 Spl, .38 Spc, (pronounced "thirty-eight special"), or 9x29mmR is a rimmed, centerfire cartridge designed by Smith & ...
and
.357 Magnum The .357 Smith & Wesson Magnum, .357 S&W Magnum, .357 Magnum, or 9×33mmR as it is known in unofficial metric designation, is a smokeless powder cartridge with a bullet diameter. It was created by Elmer Keith, Phillip B. Sharpe, and Douglas B. ...
. Snake shot may not cycle properly in semi-automatic pistols. Rifles specifically made to fire
.22 caliber .22 caliber, or 5.6 mm caliber, refers to a common firearms bore diameter of 0.22 inch (5.6 mm). Cartridges in this caliber include the very widely used .22 Long Rifle and .223 Remington / 5.56×45mm NATO. .22 inch is also a popular ...
snake shot are also commonly used by farmers for
pest control Pest control is the regulation or management of a species defined as a pest; any animal, plant or fungus that impacts adversely on human activities or environment. The human response depends on the importance of the damage done and will range ...
inside of barns and sheds, as the snake shot will not shoot holes in the roof or walls, or more importantly injure livestock with a ricochet. They are also used for airport and warehouse pest control. Shot shells have also been historically issued to soldiers, to be used in standard issue rifles. The .45-70 "Forager" round, which contained a thin wooden bullet filled with birdshot, was intended for hunting
small game Game or quarry is any wild animal hunted for animal products (primarily meat), for recreation (" sporting"), or for trophies. The species of animals hunted as game varies in different parts of the world and by different local jurisdictions, thou ...
to supplement the soldiers' rations. This round in effect made the .45-70 rifle into a small gauge
shotgun A shotgun (also known as a scattergun, or historically as a fowling piece) is a long-barreled firearm designed to shoot a straight-walled cartridge known as a shotshell, which usually discharges numerous small pellet-like spherical sub- pr ...
, capable of killing rabbits, ducks, and other small game. During World War II, the United States military developed the
.45 ACP The .45 ACP ( Automatic Colt Pistol) or .45 Auto (11.43×23mm) is a rimless straight-walled handgun cartridge designed by John Moses Browning in 1904, for use in his prototype Colt semi-automatic pistol. After successful military trials, it ...
M12 and M15 shot shells cartridges. They were issued to pilots, to be used as foraging ammunition in the event that they were shot down. While they were best used in the
M1917 revolver The M1917 Revolvers were six-shot, .45 ACP, large frame revolvers adopted by the United States Military in 1917, to supplement the standard M1911 pistol during World War I. There were two variations of the M1917, one made by Colt and the other b ...
s, the M15 cartridge would actually cycle the semi-automatic M1911 pistols action.


Garden guns

Garden guns are smooth-bore firearms specifically made to fire
.22 caliber .22 caliber, or 5.6 mm caliber, refers to a common firearms bore diameter of 0.22 inch (5.6 mm). Cartridges in this caliber include the very widely used .22 Long Rifle and .223 Remington / 5.56×45mm NATO. .22 inch is also a popular ...
snake shot, and are commonly used by gardeners and farmers for
pest control Pest control is the regulation or management of a species defined as a pest; any animal, plant or fungus that impacts adversely on human activities or environment. The human response depends on the importance of the damage done and will range ...
. Garden guns are short-range weapons that can do little harm past 15 to 20 yards, and they are quiet when fired with snake shot, compared to a standard ammunition. These guns are especially effective inside of barns and sheds, as the snake shot will not shoot holes in the roof or walls, or more importantly injure livestock with a ricochet. They are also used for pest control at airports, warehouses, stockyards, etc.


Shotgun gauge diameter formula

The standard definition of shotgun gauge assumes that a pure lead ball is used. The following formulas relate the bore diameter ''dn'' (in inches) to the gauge ''n'': :d_n = 1.67 / \sqrt = \sqrt /math> :n= (1.67 / d_n)^ = 4.66 / (d_n)^ For example, the common bore diameter ''dn'' = 0.410 inches (
.410 bore The .410 bore is one of the smallest caliber of shotgun shell commonly available (along with the 9mm Flobert rimfire cartridge, and the less common .22 rimfire shot shell). A .410 bore shotgun loaded with shot shells is well suited for small g ...
) is effectively gauge ''n'' = 67.6 .


Lead free

By 1957 the ammo industry had the capability of producing a nontoxic shot, made out of either iron or steel. In 1976 the Fish and Wildlife Service took the first steps toward phasing out lead shot by designating steel-shot-only hunting zones for waterfowl. In the 1970s lead-free shot shell ammunition loaded with steel,
bismuth Bismuth is a chemical element with the symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental bismuth occurs na ...
, or tungsten composite pellets instead of more traditional lead-based pellets was introduced and required for Migratory Bird Hunting (Ducks & Geese). Lead shot in waterfowl hunting was banned throughout the United States in 1991. Due to environmental regulations, lead-loaded ammunition must be used carefully by hunters in Europe. For instance, in France, it cannot be fired in the vicinity of a pond. In fact, the laws are so complex that some hunters in Europe prefer not to risk getting into problems for firing lead pellets in the wrong places, so they opt for composite pellets in all situations. The use of lead shot is banned in Canada and the United States when hunting migratory game birds, such as ducks and geese, forcing the use of non-toxic shot in these countries for waterfowl hunting (lead shot can still legally be used in the United States for hunting game other than waterfowl). This means that manufacturers need to market new types of lead-free shotgun ammunition loaded with alternative pellets to meet environmental restrictions on the use of lead, as well as lead-based and cheaper shotshell ammunition, to remain competitive worldwide. The C.I.P. enforces approval of all ammunition a manufacturer or importer intends to sell in any of the (mainly European) C.I.P. member states. The ammunition manufacturing plants are obliged to test their products during production against the C.I.P. pressure specifications. A compliance report must be issued for each production lot and archived for later verification if needed. Besides pressure testing, shotshells containing steel pellets require an additional Vickers hardness test. The steel pellets used must have a hardness under 100 HV1, but, even so, steel is known to wear the barrel excessively over time if the steel pellet velocities become too high, leading to potentially harmful situations for the user. As a result, the measurement of pellet velocity is also an additional obligation for shotshells in 12-, 16-, and 20-gauges in both standard and high performance versions sold in Europe. The velocity of pellets must be below , and respectively for the standard versions. Another disadvantage of steel pellets is their tendency to ricochet unpredictably after striking any hard surface. This poses a major hazard at indoor ranges or whenever metal targets or hard backstops (e.g. concrete wall vs. a dirt berm) are used. For this reason, steel shot is explicitly banned at most indoor shooting ranges. Any shooters who are considering buying ammo loaded with steel for anything other than hunting purposes should first find out if using it won't cause undue hazard to themselves and others. However, data supporting the danger of firing high velocity shells loaded with steel shot causing barrel wear has not been published and the US equivalent of CIP, SAAMI, does not have any such restrictive limitations on the velocity of commercial steel shotshells sold in the United States. Similarly, shotgun manufacturers selling shotguns in the United States select their own appropriate standards for setting steel hardness for shotgun barrels and for velocities of steel shotshell loaded ammunition. Some indoor shooting ranges prohibit the use of steel shot over concern of it causing a spark when hitting an object down range and causing a fire.


Shot sizes

Shotshells are loaded with different sizes of shot depending on the target. For skeet shooting, a small shot such as a No.8 or No.9 would be used, because range is short and a high density pattern is desirable.
Trap shooting Trap shooting, or trapshooting in North America, is one of the three major disciplines of competitive clay pigeon shooting, which is shooting shotguns at clay targets. The other disciplines are skeet shooting and sporting clays. They are disting ...
requires longer shots, and so a larger shot, usually #7½ is used. For hunting game, the range and penetration needed to assure a clean kill is considered. Shot loses its velocity very quickly due to its low
sectional density Sectional density (often abbreviated SD) is the ratio of an object's mass to its cross sectional area with respect to a given axis. It conveys how well an object's mass is distributed (by its shape) to overcome resistance along that axis. Sectio ...
and
ballistic coefficient In ballistics, the ballistic coefficient (BC, ''C'') of a body is a measure of its ability to overcome air resistance in flight. It is inversely proportional to the negative acceleration: a high number indicates a low negative acceleration—the d ...
(see external ballistics). Small shot, like that used for skeet and trap, will have lost all appreciable energy by around , which is why trap and skeet ranges can be located in relatively close proximity to inhabited areas with negligible risk of injury to those outside the range.


Birdshot

Birdshots are designed to be used for waterfowl and
upland hunting Upland hunting is an American term for a form of hunting in which the hunter pursues upland birds including quail, pheasant, grouse, woodcock, prairie chicken, chukar, grey partridge, and other landfowls. Unlike aquatic birds (waterfowls and shor ...
, where the game is agile small/medium-sized birds. Their sizes are numbered similar to the shotgun gauges—the smaller the number, the larger the shot (except in the obsolete Swedish system, in which it is reversed). Generally birdshot is just called "shot", such as "number 9 shot" or "BB shot". There are small differences in size of American, Standard (European), Belgian, Italian, Norwegian, Spanish, Swedish, British, and Australian shot to make matters more complex. That is because some systems go by diameter in inches (American), some go by diameter in millimeters (European), and the British system goes by the number of lead shot per ounce. Australia has a hybrid system due to its market being flooded with a mixture of British, American, and European shells. For American shot, a useful method for remembering the diameter of numbered shot in inches is simply to subtract the shot size from 17. The resulting answer is the diameter of the shot in hundredths of an inch. For example, #2 shot gives 17-2 = 15, meaning that the diameter of #2 shot is 15/100 or . B shot is , and sizes go up in increments for BB and BBB sizes. In metric measurement, it is easy to remember that #5 shot is 3 mm; each number up or down represents a 0.25 mm change in diameter, so e.g. #7 shot is 2.5 mm. Number 11 and number 12 lead shot also exists. Shot of these sizes is used in specialized shotshells designed to be fired at close range (less than four yards) for killing snakes, rats and similar-sized animals. Such shells are typically intended to be fired from handguns, particularly revolvers. This type of ammunition is produced by Federal and CCI, among others.


Birdshot selection

For hunting, shot size must be chosen not only for the range, but also for the game. The shot must reach the target with enough energy to penetrate to a depth sufficient to kill the game. Lead shot is still the best ballistic performer, but environmental restrictions on the use of lead, especially with waterfowl, require steel,
bismuth Bismuth is a chemical element with the symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental bismuth occurs na ...
, or tungsten composites. Steel, being significantly less dense than lead, requires larger shot sizes, but is a good choice when lead is not legal and cost is a consideration. It is argued that steel shot cannot safely be used in some older shotguns without causing damage to either the bore or to the choke due to the hardness of steel shot. However, the increased pressure in most steel cartridges is a far greater problem, causing more strain to the breech of the gun. Since tungsten is very hard, it must also be used with care in older guns. Tungsten shot is often alloyed with nickel and iron, softening the base metal. That alloy is approximately 1/3 denser than lead, but far more expensive. Bismuth shot falls between steel and tungsten shot in both density and cost. The rule of thumb in converting appropriate steel shot is to go up by two numbers when switching from lead. However, there are different views on dense patterns versus higher pellet energies.


Buckshot

Larger sizes of shot, large enough that they must be carefully packed into the shell rather than simply dumped or poured in, are called "buckshot" or just "buck". Buckshot is used for hunting medium to large game, as a tactical round for law enforcement and military personnel, and for personal self-defense. Buckshot size is most commonly designated by a series of numbers and letters, with smaller numbers indicating larger shot. Sizes larger than "0" are designated by multiple zeros. "00" (usually pronounced "double-aught" in North American English) is the most commonly sold size. The British system for designating buckshot size is based on the amount of shot per ounce. The sizes are LG (large grape – from grapeshot derived from musket shooting), MG (medium grape), and SG (small grape). For smaller game, SSG shot is half the weight of SG, SSSG shot is half the weight of SSG, SSSSG shot is half the weight of SSSG, and so on. The Australian system is similar, except that it has 00-SG, a small-game shell filled with 00 buckshot. Loads of 12-gauge 00 buckshot are commonly available in cartridges holding from 8 (eight) to 18 (eighteen) pellets in standard shell lengths ( inches, 3 inches, and ). Reduced-recoil 00 buckshot shells are often used as tactical and self-defense rounds, minimizing shooter stress and improving the speed of follow-up shots.


Spread and patterning

Most modern sporting shotguns have interchangeable choke tubes to allow the shooter to change the spread of shot that comes out of the gun. In some cases, it is not practical to do this; the gun might have fixed choke, or a shooter firing at receding targets may want to fire a wide pattern immediately followed by a narrower pattern out of a single barrelled shotgun. The spread of the shot can also be altered by changing the characteristics of the shell.


Narrower patterns

A buffering material, such as granulated plastic, sawdust, or similar material can be mixed with the shot to fill the spaces between the individual pellets. When fired, the buffering material compresses and supports the shot, reducing the
deformation Deformation can refer to: * Deformation (engineering), changes in an object's shape or form due to the application of a force or forces. ** Deformation (physics), such changes considered and analyzed as displacements of continuum bodies. * Defo ...
the shot pellets experience under the extreme acceleration. Antimony-lead alloys, copper plated lead shot, steel, bismuth, and tungsten composite shot all have a hardness greater than that of plain lead shot, and will deform less as well. Reducing the deformation will result in tighter patterns, as the spherical pellets tend to fly straighter. One improvised method for achieving the same effect involves pouring molten wax or tar into the mass of shot. Another is a partial ring cut around the case intended to ensure that the shot comes out tightly bunched along with the portion of the case forward of the cut, creating a 'cut-shell'. This can be dangerous, as it is thought to cause higher chamber pressures—especially if part of the shell remains behind in the barrel and is not cleared before another shot is fired.


Wider patterns

Shooting the softest possible shot will result in more shot deformation and a wider pattern. This is often the case with cheap ammunition, as the lead used will have minimal alloying elements such as antimony and be very soft. Spreader wads are wads that have a small plastic or paper insert in the middle of the shot cup, usually a cylinder or "X" cross-section. When the shot exits the barrel, the insert helps to push the shot out from the center, opening up the pattern. Often these result in inconsistent performance, though modern designs are doing much better than the traditional improvised solutions. Intentionally deformed shot (hammered into ellipsoidal shape) or cubical shot will also result in a wider pattern, much wider than spherical shot, with more consistency than spreader wads. Spreader wads and non-spherical shot are disallowed in some competitions. Hunting loads that use either spreaders or non-spherical shot are usually called "brush loads", and are favored for hunting in areas where dense cover keeps shot distances very short.


Spread

Most shotgun shells contain multiple pellets in order to increase the likelihood of a target being hit. A shotgun's shot spread refers to the two-dimensional pattern that these projectiles (or shot) leave behind on a target. Another less important dimension of spread concerns the length of the in-flight shot string from the leading pellet to the trailing one. The use of multiple pellets is especially useful for hunting small game such as birds, rabbits, and other animals that fly or move quickly and can unpredictably change their direction of travel. However, some shotgun shells only contain one metal shot, known as a
slug Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc. The word ''slug'' is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a smal ...
, for hunting large game such as deer. As the shot leaves the barrel upon firing, the three-dimensional shot string is close together. But as the shot moves farther away, the individual pellets increasingly spread out and disperse. Because of this, the effective range of a
shotgun A shotgun (also known as a scattergun, or historically as a fowling piece) is a long-barreled firearm designed to shoot a straight-walled cartridge known as a shotshell, which usually discharges numerous small pellet-like spherical sub- pr ...
, when firing a multitude of shot, is limited to approximately . To control this effect, shooters may use a constriction within the barrel of a shotgun called a choke. The choke, whether selectable or fixed within a barrel, effectively reduces the diameter of the end of the barrel, forcing the shot even closer together as it leaves the barrel, thereby increasing the effective range. The tighter the choke, the narrower the end of the barrel. Consequently, the effective range of a shotgun is increased with a tighter choke, as the shot column is held tighter over longer ranges. Hunters or target shooters can install several types of chokes, on guns having selectable chokes, depending on the range at which their intended targets will be located. For fixed choke shotguns, different shotguns or barrels are often selected for the intended hunting application at hand. From tightest to loosest, the various choke sizes are: full choke, improved modified, modified, improved cylinder, skeet, and cylinder bore. A hunter who intends to hunt an animal such as rabbit or
grouse Grouse are a group of birds from the order Galliformes, in the family Phasianidae. Grouse are presently assigned to the tribe Tetraonini (formerly the subfamily Tetraoninae and the family Tetraonidae), a classification supported by mitochondri ...
knows that the animal will be encountered at a close range—usually within —and will be moving very quickly. So, an ideal choke would be a cylinder bore (the loosest) as the hunter wants the shot to spread out as quickly as possible. If this hunter were using a full choke (the tightest) at , the shot would be very close together and cause an unnecessarily large amount of damage to the rabbit, or, alternatively, a complete miss of the rabbit. This would waste virtually all of the meat for a hit, as the little amount of meat remaining would be overly-laden with shot and rendered inedible. By using a cylinder bore, this hunter would maximize the likelihood of a kill, and maximize the amount of edible meat. Contrarily, a hunter who intends to hunt geese knows that a goose will likely be approximately away, so that hunter would want to delay the spread of the shot as much as possible by using a full choke. By using a full choke for targets that are farther away, the shooter again maximizes the likelihood of a kill, and maximizes the amount of edible meat. This also maximizes the chances of a swift and humane kill as the target would be hit with enough shot to kill quickly instead of only wounding the animal. For older shotguns having only one fixed choke, intended primarily for equally likely use against rabbits, squirrels, quail, doves, and pheasant, an often-chosen choke is the improved cylinder, in a barrel, making the shotgun suitable for use as a general all-round hunting shotgun, without having excess weight. Shotguns having fixed chokes intended for geese, in contrast, are often found with full choke barrels, in longer lengths, and are much heavier, being intended for fixed use within a blind against distant targets. Defensive shotguns with fixed chokes generally have a cylinder bore choke. Likewise, shotguns intended primarily for use with slugs invariably also are found with a choke that is a cylinder bore.


Dram equivalence

"Dram" equivalence is sometimes still used as a measure of the powder charge power in a shotgun shell. Today, it is an anachronistic equivalence that represents the equivalent power of a shotgun shell containing this equivalent amount of black-powder measured in drams avoirdupois. A dram in the
avoirdupois The avoirdupois system (; abbreviated avdp.) is a measurement system of weights that uses pounds and ounces as units. It was first commonly used in the 13th century AD and was updated in 1959. In 1959, by international agreement, the defini ...
system is the mass of   pound or  
ounce The ounce () is any of several different units of mass, weight or volume and is derived almost unchanged from the , an Ancient Roman unit of measurement. The avoirdupois ounce (exactly ) is avoirdupois pound; this is the United States customa ...
or 27.3 grains. The reasoning behind this archaic equivalence is that when smokeless powder first came out, some method of establishing an equivalence with common shotgun shell loads was needed in order to sell a box of shotgun shells. For example, a shotgun shell containing a 3 or 3 1/2 dram load of black-powder was a common hunting field load, and a heavy full power load would have contained about a 4 to 4-1/2 dram load, whereas a shotgun shell containing only a 2 dram load of black-powder was a common target practice load. A hunter looking for a field or full power load familiar with black-powder shotgun loads would have known exactly what the equivalence of the shotgun shells would have been in the newly introduced smokeless powder. Today, however, this represents a poorly understood equivalence of the powder charge power in a shotgun shell. To further complicate matters, "dram" equivalence was only defined for 12 gauge shotgun shells, and only for lead shot, although it has often been used for describing other gauges of shells, and even steel shot loaded shells. Furthermore, "dram" equivalence only came around about 15 years after smokeless powder had been introduced, long after the need for an equivalence had started to fade, and actual black-powder loaded shotshells had largely vanished. In practice, "dram" equivalence today most commonly equates just to a velocity rating equivalence in fps (feet-per-second), while assuming lead shot. A secondary impact of this equivalence was that common shotgun shells needed to stay the same size, physically, e.g., 2-1/2 or 2-3/4-inch shells, in order to be used in pre-existing shotguns when smokeless powder started being used to load shotgun shells in the place of black-powder. As smokeless powder did not have to be loaded in the same volume as black-powder to achieve the same power, being more powerful, the volumes of wads had to increase, to fill the shotgun shell enough to permit proper crimps still to be made. Initially, this meant that increased numbers of over powder card wads had to be stacked to achieve the same stack-up length. Eventually, this also led to the introduction of one-piece plastic wads in the late 1950s through the early 1960s, to add additional wad volumes, in order to maintain the same overall shotgun shell length. Dram equivalence has no bearing on the reloading of shotgun shells with smokeless powder; loading a shotgun shell with an equivalent dram weight of smokeless powder would cause a shotgun to explode. It only has an equivalence in the reloading of shotgun shells with black powder.


See also

* Gauges **
2 bore Two bore or 2 bore is a mostly obsolete firearm caliber. Specifications Two bores generally fire spherical balls or slugs of hardened lead or, in the modern metallic cartridge, additionally a solid bronze projectile. The nominal bore is , and pr ...
**
4 bore Four bore or 4 bore is a mostly obsolete black powder caliber of the 19th century, used for the hunting of large and potentially dangerous game animals. The specifications place this caliber between the larger two bore and the lesser six bore. Th ...
**
6 bore 6 (six) is the natural number following 5 and preceding 7. It is a composite number and the smallest perfect number. In mathematics Six is the smallest positive integer which is neither a square number nor a prime number; it is the second ...
**
8 bore The 8 bore, also known as the 8 gauge, is an obsolete caliber used commonly in the 19th-century black-powder firearms. Design An 8 bore is a caliber firearm. Historically it was used to fire solid projectiles from smoothbores, rifles, and part ...
**
20-gauge shotgun The 20- gauge shotgun, also known as "20-bore", is a type of smooth-bore shotgun that fires a shell that is smaller in caliber () than a 12-gauge shotgun (). It is often used by beginning shooters for target practice and for hunting small game. ...
**
.410 bore The .410 bore is one of the smallest caliber of shotgun shell commonly available (along with the 9mm Flobert rimfire cartridge, and the less common .22 rimfire shot shell). A .410 bore shotgun loaded with shot shells is well suited for small g ...
*
Breaching round A breaching round or slug-shot is a shotgun shell specially made for door breaching. It is typically fired at a range of 6 inches (15 cm) or less, aimed at the hinges or the area between the doorknob and lock and doorjamb, and is designed to ...
* Lead shot *
Snake shot Snake shot (also commonly known as rat shot and dust shot) refers to handgun and rifle cartridges loaded with lead shot canisters instead of bullets, much like large caliber canister shot. Snake shot is generally used for shooting snakes, roden ...
* Red rocket, a
3D print 3D printing or additive manufacturing is the construction of a three-dimensional object from a CAD model or a digital 3D model. It can be done in a variety of processes in which material is deposited, joined or solidified under computer c ...
ed shotgun slug as a politically motivated demonstration of its possibility *
Shotgun slug A shotgun slug is a heavy projectile made of lead, copper, or other material and fired from a shotgun. Slugs are designed for hunting large game, and other uses, particularly in areas near human population where their short range and slow speed h ...
* Shrapnel shell * Rifle cartridge


References


External links

* {{DEFAULTSORT:Shotgun Shell zh-yue:霰彈 Paramilitary cartridges Shotgun shells