Gun barrel
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A gun barrel is a crucial part of gun-type
weapon A weapon, arm, or armament is any implement or device that is used to deter, threaten, inflict physical damage, harm, or kill. Weapons are used to increase the efficacy and efficiency of activities such as hunting, crime (e.g., murder), law ...
s such as
small Small means of insignificant size Size in general is the Magnitude (mathematics), magnitude or dimensions of a thing. More specifically, ''geometrical size'' (or ''spatial size'') can refer to three geometrical measures: length, area, or ...
firearm A firearm is any type of gun that uses an explosive charge and is designed to be readily carried and operated by an individual. The term is legally defined further in different countries (see legal definitions). The first firearms originate ...
s, artillery pieces, and air guns. It is the straight
shooting Shooting is the act or process of discharging a projectile from a ranged weapon (such as a gun, bow, crossbow, slingshot, or blowpipe). Even the acts of launching flame, artillery, darts, harpoons, grenades, rockets, and guided missile ...
tube, usually made of rigid high-strength
metal A metal () is a material that, when polished or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, electricity and thermal conductivity, heat relatively well. These properties are all associated wit ...
, through which a contained rapid expansion of high-pressure gas(es) is used to propel a
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 ...
out of the front end ( muzzle) at a high velocity. The hollow interior of the barrel is called the bore, and the
diameter In geometry, a diameter of a circle is any straight line segment that passes through the centre of the circle and whose endpoints lie on the circle. It can also be defined as the longest Chord (geometry), chord of the circle. Both definitions a ...
of the bore is called its calibre, usually measured in inches or millimetres. The first firearms were made at a time when
metallurgy Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are known as alloys. Metallurgy encompasses both the ...
was not advanced enough to cast tubes capable of withstanding the explosive forces of early
cannon A cannon is a large-caliber gun classified as a type of artillery, which usually launches a projectile using explosive chemical propellant. Gunpowder ("black powder") was the primary propellant before the invention of smokeless powder during th ...
s, so the pipe (often built from staves of metal) needed to be braced periodically along its length for structural reinforcement, producing an appearance somewhat reminiscent of storage
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 stave (wood), staves and bound by wooden or metal hoops. The word vat is often used for large containers ...
s being stacked together, hence the English name.


History

Gun barrels are usually made of some type of metal or metal alloy. However, during the late
Tang dynasty The Tang dynasty (, ; zh, c=唐朝), or the Tang Empire, was an Dynasties of China, imperial dynasty of China that ruled from 618 to 907, with an Wu Zhou, interregnum between 690 and 705. It was preceded by the Sui dynasty and followed ...
, Chinese inventors discovered
gunpowder 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, charcoal (which is mostly carbon), and potassium nitrate, potassium ni ...
, and used
bamboo Bamboos are a diverse group of mostly evergreen perennial plant, perennial flowering plants making up the subfamily (biology), subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family, in th ...
, which has a strong, naturally tubular stalk and is cheaper to obtain and process, as the first barrels in gunpowder projectile weapons such as fire lances. The Chinese were also the first to master
cast-iron Cast iron is a class of iron–carbon alloys with a carbon content of more than 2% and silicon content around 1–3%. Its usefulness derives from its relatively low melting temperature. The alloying elements determine the form in which its car ...
cannon barrels, and used the technology to make the earliest infantry firearms — the hand cannons. Early European guns were made of
wrought iron Wrought iron is an iron alloy with a very low carbon content (less than 0.05%) in contrast to that of cast iron (2.1% to 4.5%), or 0.25 for low carbon "mild" steel. Wrought iron is manufactured by heating and melting high carbon cast iron in an ...
, usually with several strengthening bands of the metal wrapped around circular wrought iron rings and then welded into a hollow cylinder.
Bronze Bronze is an alloy consisting primarily of copper, commonly with about 12–12.5% tin and often with the addition of other metals (including aluminium, manganese, nickel, or zinc) and sometimes non-metals (such as phosphorus) or metalloid ...
and
brass Brass is an alloy of copper and zinc, in proportions which can be varied to achieve different colours and mechanical, electrical, acoustic and chemical properties, but copper typically has the larger proportion, generally copper and zinc. I ...
were favoured by
gunsmith A gunsmith is a person who repairs, modifies, designs, or builds guns. The occupation differs from an armorer, who usually replaces only worn parts in standard firearms. Gunsmiths do modifications and changes to a firearm that may require a very ...
s, largely because of their ease of casting and their resistance to the corrosive effects of the combustion of gunpowder or salt water when used on naval vessels. Early
firearm A firearm is any type of gun that uses an explosive charge and is designed to be readily carried and operated by an individual. The term is legally defined further in different countries (see legal definitions). The first firearms originate ...
s were
muzzleloaders A muzzleloader is any firearm in which the user loads the bullet, projectile and the propellant charge into the Muzzle (firearms), muzzle end of the gun (i.e., from the forward, open end of the gun's barrel). This is distinct from the modern desi ...
, with the
gunpowder 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, charcoal (which is mostly carbon), and potassium nitrate, potassium ni ...
and then the shot loaded from the front end (muzzle) of the barrel, and were capable of only a low rate of fire due to the cumbersome loading process. The later-invented breech-loading designs provided a higher rate of fire, but early breechloaders lacked an effective way of sealing the escaping gases that leaked from the back end (breech) of the barrel, reducing the available muzzle velocity. During the 19th century, effective breechblocks were invented that sealed a breechloader against the escape of propellant gases. Early cannon barrels were very thick for their calibre. This was because manufacturing defects such as air bubbles trapped in the metal were common at that time, and played key factors in many gun explosions; these defects made the barrel too weak to withstand the pressures of firing, causing it to fail and fragment explosively.


Construction

A gun barrel must be able to hold in the expanding gas produced by the
propellant A propellant (or propellent) is a mass that is expelled or expanded in such a way as to create a thrust or another motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicle ...
s to ensure that optimum muzzle velocity is attained by the projectile as it is being pushed out. If the barrel material cannot cope with the pressure within the bore, the barrel itself might suffer
catastrophic failure A catastrophic failure is a sudden and total failure from which recovery is impossible. Catastrophic failures often lead to cascading systems failure. The term is most commonly used for structural failures, but has often been extended to many ot ...
and explode, which will not only destroy the gun but also present a life-threatening danger to people nearby. Modern
small arms A firearm is any type of gun that uses an explosive charge and is designed to be readily carried and operated by an individual. The term is legally defined further in different countries (see legal definitions). The first firearms originate ...
barrels are made of
carbon steel Carbon steel is a steel with carbon content from about 0.05 up to 2.1 percent by weight. The definition of carbon steel from the American Iron and Steel Institute (AISI) states: * no minimum content is specified or required for chromium, cobalt ...
or
stainless steel Stainless steel, also known as inox, corrosion-resistant steel (CRES), or rustless steel, is an iron-based alloy that contains chromium, making it resistant to rust and corrosion. Stainless steel's resistance to corrosion comes from its chromi ...
materials known and tested to withstand the pressures involved. Artillery pieces are made by various techniques providing reliably sufficient strength.


Fluting

Fluting is the removal of material from a cylindrical surface, usually creating rounded grooves, for the purpose of reducing weight. This is most often done to the exterior surface of a rifle barrel, though it may also be applied to the cylinder of a
revolver A revolver is a repeating handgun with at least one barrel and a revolving cylinder containing multiple chambers (each holding a single cartridge) for firing. Because most revolver models hold six cartridges before needing to be reloaded, ...
or the bolt of a bolt-action rifle. Most flutings on rifle barrels and revolver cylinders are straight, though helical flutings can be seen on rifle bolts and occasionally also rifle barrels. While the main purpose of fluting is just to reduce weight and improve portability, when adequately done it can retain the structural strength and rigidity and increase the overall specific strength. Fluting will also increase the surface-to-volume ratio and make the barrel more efficient to cool after firing, though the reduced material mass also means the barrel will heat up easily during firing.


Composite barrels

A composite barrel is a firearm barrel that has been shaved down to be thinner and an exterior sleeve slipped over and fused to it that improves rigidity, weight and cooling. Most common form of composite barrel are those with
carbon fibre Carbon fiber-reinforced polymers (American English), carbon-fibre-reinforced polymers ( Commonwealth English), carbon-fiber-reinforced plastics, carbon-fiber reinforced-thermoplastic (CFRP, CRP, CFRTP), also known as carbon fiber, carbon comp ...
sleeves, but there are proprietary examples such as the Teludyne Tech Straitjacket. They are seldom used outside sports and competition shooting.


Mounting

A barrel can be fixed to the receiver using action threads or rivets. Depending on construction different gun barrels can be used: * common fixed barrel for firearms * interchangeable barrel for firearms * quick-change barrel for machineguns * replacement gun barrel (spare barrel) for artilleryguns


Components


Chamber

The chamber is the cavity at the back end of a breech-loading gun's barrel where the cartridge is inserted in position ready to be fired. In most firearms (
rifle A rifle is a long gun, long-barreled firearm designed for accurate shooting and higher stopping power, with a gun barrel, barrel that has a helical or spiralling pattern of grooves (rifling) cut into the bore wall. In keeping with their focus o ...
s, shotguns, machine guns and pistols), the chamber is an integral part of the barrel, often made by simply reaming the rear bore of a barrel blank, with a single chamber within a single barrel. In
revolver A revolver is a repeating handgun with at least one barrel and a revolving cylinder containing multiple chambers (each holding a single cartridge) for firing. Because most revolver models hold six cartridges before needing to be reloaded, ...
s, the chamber is a component of the gun's cylinder and completely separate from the barrel, with a single cylinder having multiple chambers that are rotated in turns into alignment with the barrel in anticipation of being fired. Structurally, the chamber consists of the body, shoulder and neck, the contour of which closely correspond to the casing shape of the cartridge it is designed to hold. The rear opening of the chamber is the breech of the whole barrel, which is sealed tight from behind by the bolt, making the front direction the path of least resistance during firing. When the cartridge's primer is struck by the firing pin, the
propellant A propellant (or propellent) is a mass that is expelled or expanded in such a way as to create a thrust or another motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicle ...
is ignited and deflagrates, generating high-pressure gas expansion within the cartridge case. However, the chamber (closed from behind by the bolt) restrains the cartridge case (or
shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses Science Biology * Seashell, a hard outer layer of a marine ani ...
for shotguns) from moving, allowing the
bullet A bullet is a kinetic projectile, a component of firearm ammunition that is shot from a gun barrel. They are made of a variety of materials, such as copper, lead, steel, polymer, rubber and even wax; and are made in various shapes and constru ...
(or shot/
slug Slug, or land slug, is a common name for any apparently shell-less Terrestrial mollusc, 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 ...
in shotguns) to separate cleanly from the casing and be propelled forward along the barrel to exit out of the front (muzzle) end as a flying
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 ...
. Chambering a gun is the process of loading a cartridge into the gun's chamber, either manually as in single loading, or via operating the weapon's own action as in pump action, lever action, bolt action or self-loading actions. In the case of an air gun, a pellet (or slug) itself has no casing to be retained and will be entirely inserted into the chamber (often called "seating" or "loading" the pellet, rather than "chambering" it) before a mechanically pressurized gas is released behind the pellet and propels it forward, meaning that an air gun's chamber is functionally equivalent to the freebore portion of a firearm barrel. In the context of firearms design, manufacturing and modification, the word "chambering" has a different meaning, and refers to fitting a weapon's chamber specifically to fire a particular
caliber In guns, particularly firearms, but not #As a measurement of length, artillery, where a different definition may apply, caliber (or calibre; sometimes abbreviated as "cal") is the specified nominal internal diameter of the gun barrel Gauge ( ...
or model of cartridge.


Bore

The bore is the hollow internal lumen of the barrel, and takes up a vast majority portion of the barrel length. It is the part of the barrel where the projectile (bullet, shot, or slug) is located prior to firing and where it gains
speed In kinematics, the speed (commonly referred to as ''v'') of an object is the magnitude of the change of its position over time or the magnitude of the change of its position per unit of time; it is thus a non-negative scalar quantity. Intro ...
and
kinetic energy In physics, the kinetic energy of an object is the form of energy that it possesses due to its motion. In classical mechanics, the kinetic energy of a non-rotating object of mass ''m'' traveling at a speed ''v'' is \fracmv^2.Resnick, Rober ...
during the firing process. The projectile's status of
motion In physics, motion is when an object changes its position with respect to a reference point in a given time. Motion is mathematically described in terms of displacement, distance, velocity, acceleration, speed, and frame of reference to an o ...
while travelling down the bore is referred to as its
internal ballistics Internal ballistics (also interior ballistics), a subfield of ballistics, is the study of the propulsion of a projectile. In guns, internal ballistics covers the time from the propellant's ignition until the projectile exits the gun barrel. The s ...
. Most modern firearms (except
musket A musket is a muzzle-loaded long gun that appeared as a smoothbore weapon in the early 16th century, at first as a heavier variant of the arquebus, capable of penetrating plate armour. By the mid-16th century, this type of musket gradually dis ...
s, shotguns, most tank guns, and some artillery pieces) and air guns (except some BB guns) have helical grooves called ''riflings'' machined into the bore wall. When shooting, a rifled bore imparts spin to the projectile about its longitudinal axis, which gyroscopically stabilizes the projectile's
flight Flight or flying is the motion (physics), motion of an Physical object, object through an atmosphere, or through the vacuum of Outer space, space, without contacting any planetary surface. This can be achieved by generating aerodynamic lift ass ...
attitude Attitude or Attitude may refer to: Philosophy and psychology * Attitude (psychology), a disposition or state of mind ** Attitude change * Propositional attitude, a mental state held towards a proposition Science and technology * Orientation ...
and
trajectory A trajectory or flight path is the path that an object with mass in motion follows through space as a function of time. In classical mechanics, a trajectory is defined by Hamiltonian mechanics via canonical coordinates; hence, a complete tra ...
after its exit from the barrel (i.e. the external ballistics). Any gun without riflings in the bore is called a '' smoothbore'' gun. When a firearm cartridge is chambered, its casing occupies the chamber but its bullet actually protrudes beyond the chamber into the posterior end of the bore. Even in a rifled bore, this short rear section is without rifling, and allows the bullet an initial "run-up" to build up
momentum In Newtonian mechanics, momentum (: momenta or momentums; more specifically linear momentum or translational momentum) is the product of the mass and velocity of an object. It is a vector quantity, possessing a magnitude and a direction. ...
before encountering riflings during shooting. The most posterior part of this unrifled section is called a ''freebore'', and is usually cylindrical. The portion of the unrifled bore immediately front of the freebore, called the ''leade'', starts to taper slightly and guides the bullet towards the area where the riflingless bore transitions into fully rifled bore. Together they form the throat region, where the riflings impactfully "bite" into the moving bullet during shooting. The throat is subjected to the greatest thermomechanical stress and therefore suffers
wear Wear is the damaging, gradual removal or deformation of material at solid surfaces. Causes of wear can be mechanical (e.g., erosion) or chemical (e.g., corrosion). The study of wear and related processes is referred to as tribology. Wear in ...
the fastest. Throat erosion is often the main determining factor of a gun's barrel life.


Muzzle

The muzzle is the front end of a barrel from which the projectile will exit.Quertermous & Quertermous, p. 429 f. Precise
machining Machining is a manufacturing process where a desired shape or part is created using the controlled removal of material, most often metal, from a larger piece of raw material by cutting. Machining is a form of subtractive manufacturing, which util ...
of the muzzle is crucial to accuracy, because it is the last point of contact between the barrel and the projectile. If inconsistent gaps exist between the muzzle and the projectile, escaping propellant gases may spread unevenly and deflect the projectile from its intended path (see transitional ballistics). The muzzle can also be threaded on the outside to allow the attachment of different accessory devices. In rifled barrels, the contour of a muzzle is designed to keep the rifling safe from damage by intruding foreign objects, so the front ends of the rifling grooves are commonly protected behind a recessed crown, which also serves to modulate the even expansion of the propellant gases. The crown itself is often recessed from the outside rim of the muzzle to avoid accidental damage from collision with the surrounding environment. In smooth bore barrels firing multiple sub-projectiles (such as shotgun shot), the bore at the muzzle end might have a tapered constriction called '' choke'' to shape the scatter pattern for better range and accuracy. Chokes are implemented as either interchangeable screw-in chokes for particular applications, or as fixed permanent chokes integral to the barrel. During firing, a bright flash of light known as a '' muzzle flash'' is often seen at the muzzle. This flash is produced by both superheated propellant gases radiating energy during expansion (primary flash), and the incompletely combusted propellant residues reacting vigorously with the fresh supply of ambient air upon escaping the barrel (secondary flash). The size of the flash depends on factors such as barrel length (shorter barrels have less time for complete combustion, hence more unburnt powder), the type (fast- vs. slow-burning) and amount of propellant (higher total amount means likely more unburnt residues) loaded in the cartridge. Flash suppressors or muzzle shrouds can be attached to the muzzle of the weapon to either diminish or conceal the flash. The rapid expansion of propellant gases at the muzzle during firing also produce a powerful shockwave known as a '' muzzle blast''. The audible component of this blast, also known as a ''muzzle report'', is the loud "bang" sound of gunfire that can easily exceed 140
decibel The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a Power, root-power, and field quantities, power or root-power quantity on a logarithmic scale. Two signals whos ...
s and cause permanent hearing loss to the shooter and bystanders. The non-audible component of the blast is an infrasonic
overpressure Overpressure (or blast overpressure) is the pressure caused by a shock wave over and above normal atmospheric pressure. The shock wave may be caused by sonic boom or by explosion An explosion is a rapid expansion in volume of a given amoun ...
wave that can cause damage to nearby fragile objects. Accessory devices such as muzzle brakes and muzzle boosters can be used to redirect muzzle blast in order to counter the recoil-induced
muzzle rise Muzzle rise, muzzle flip or muzzle climb refers to the tendency of a firearm's or airgun's Muzzle (firearms), muzzle (front end of the Gun barrel, barrel) to rise up after firing. It more specifically refers to the seemingly unpredictable "jump" ...
or to assist the gas operation of the gun, and
suppressor A silencer, also known as a sound suppressor, suppressor, or sound moderator, is a gun barrel#Muzzle, muzzle device that suppresses the muzzle blast, blast created when a gun (firearm or airgun) is discharged, thereby reducing the sound inten ...
s (and even muzzle shrouds) can be used to reduce the blast noise intensity felt by nearby personnel.


See also

* Bore evacuator * Bore snake * Cap gun * Caplock mechanism * Minié ball *
Muzzleloader A muzzleloader is any firearm in which the user loads the bullet, projectile and the propellant charge into the Muzzle (firearms), muzzle end of the gun (i.e., from the forward, open end of the gun's barrel). This is distinct from the modern desi ...
* Polygonal rifling * Slug barrel * Smoothbore barrel, opposite of a
rifling Rifling is the term for helical grooves machined into the internal surface of a firearms's barrel for imparting a spin to a projectile to improve its aerodynamic stability and accuracy. It is also the term (as a verb) for creating such groov ...
barrel * Tubes and primers for ammunition


References


Bibliography

* {{DEFAULTSORT:Gun Barrel Artillery components Firearm components