with its massive bore and the stacked barrel
A gun barrel is a crucial part of gun
-type ranged weapon
s such as small firearm
s, artillery piece
s and air gun
s. It is the straight shooting
tube, usually made of rigid high-strength metal
, through which a contained rapid expansion of high-pressure gas(es) is used to propel a projectile out of the front end (muzzle
) at a high velocity. The hollow interior of the barrel is called the bore, and the diameter
of the bore is called its caliber
, usually measured in inches
The first firearms were made at a time when metallurgy
was not advanced enough to cast tubes capable of withstanding the explosive forces of early cannon
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
s being stacked together, hence the English
[''A History of Warfare'' - Keegan, John, Vintage 1993]
Gun barrels are usually metal. However, the early Chinese, the inventors of gunpowder, used bamboo
, which has a strong, naturally tubular stalk and is cheaper to obtain and process, as the first barrels in gunpowder projectile weapons such as the fire lance
The Chinese were also the first to master cast-iron
cannon barrels, and used the technology to make the earliest infantry firearms — the hand cannon
s. Early European guns were made of wrought iron
, usually with several strengthening bands of the metal wrapped around circular wrought iron rings and then welded into a hollow cylinder.
were favoured by gunsmith
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.
s were muzzle-loading
, with the gunpowder
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 breechblock
s were invented that sealed a breechloader against the escape of propellant gases.
Early cannon barrels were very thick for their caliber
. 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.
in use in 1944]]
A gun barrel must be able to hold in the expanding gas produced by the propellant
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
and explode, which will not only destroy the gun but also present a life-threatening danger to people nearby. Modern small arms
barrels are made of carbon steel
or stainless steel
materials known and tested to withstand the pressures involved. Artillery pieces are made by various techniques providing reliably sufficient strength.
with fluted barrel]]
In firearms terminology, fluting refers to 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 (firearms)|cylinder
of a revolver
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 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.
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 fiber
sleeves, but there are proprietary examples such as the Teludyne Tech Straitjacket. They are seldom used outside sports and competition shooting
A barrel can be fixed to the receiver using action threads
or similar methods.
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
s, machine gun
s and pistol
s), 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
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
is ignited and deflagrate
s, generating high-pressure gas expansion within the cartridge case. However, the chamber (closed from behind by the bolt) restrains the cartridge case (or shell
) from moving, allowing the bullet
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
The act of ''chambering'' a gun refers to 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
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
or model of cartridge.
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
, or slug
) is located prior to firing and where it gains speed
and kinetic energy
during the firing process. The projectile's status of motion
while travelling down the bore is referred to as its internal ballistics
Most modern firearms (except musket
s, most tank gun
s, and some artillery piece
s) and air guns (except some BB gun
s) have helical grooves called rifling
s machined into the bore wall. When shooting, a rifled bore imparts spin to the projectile about its longitudinal axis, which gyroscopic
ally stabilizes the projectile's flight attitude
after its exit from the barrel (i.e. the external ballistics
). Any gun without riflings in the bore is called a ''smoothbore
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
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
the fastest. Throat erosion is often the main determining factor of a gun's barrel life.
thumb|Muzzle of a SIG 550
rifle, equipped with a birdcage-type [[flash suppressor ]]
[[File:Shotgun-Chokes-Basic.png|thumb|Various types of [[shotgun]] [[choke (firearms)|choke]]s]]
The muzzle is the front end of a barrel from which the projectile
[Quertermous & Quertermous, pp.429]
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.
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 residue
s 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 suppressor
s or muzzle shroud
s 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 decibels and cause permanent hearing loss to the shooter and bystanders. The non-audible component of the blast is an infrasonic overpressure 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 or to assist the gas operation of the gun, and suppressors (and even muzzle shrouds) can be used to reduce the blast noise intensity felt by nearby personnel.
*Tubes and primers for ammunition