Gun barrel

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(Redirected from
Muzzle (firearm)
)
The Tsar Cannon of 1586 with its huge bore and a barrel exterior which is perceived like a stack of storage barrels

A gun barrel is a crucial part of

millimetres
.

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 cannons, 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 barrels being stacked together, hence the English name.[1]

History

WWI

Gun barrels are usually made of some type of metal or

cast-iron cannon barrels, and used the technology to make the earliest infantry firearms — the hand cannons. 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.[3] Bronze and brass were favoured by gunsmiths, 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.[4]

Early

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.[5] During the 19th century, effective breechblocks were invented that sealed a breechloader against the escape of propellant gases.[6]

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.[7]

Construction

The barrel of a 240 mm howitzer in use in 1944

A gun barrel must be able to hold in the expanding gas produced by the

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.[8][9]

Fluting

A German Army G22 with fluted barrel

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

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

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 fiber 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 similar methods.

Components

Chamber

Springfield M1903
.
Illustration of the various sections of a typical rifle chamber. The back end is to the left, and the front is to the right. Body (purple), shoulder (pink) and neck (green).

The chamber is the cavity at the back end of a

reaming the rear bore of a barrel blank, with a single chamber within a single barrel.[10] In revolvers, 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

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 for shotguns) from moving, allowing the bullet (or shot/slug 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
.

Chambering a gun is the process of loading a cartridge into the gun's chamber, either manually as in

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 or model of cartridge.

Bore

  Conventional rifling
A = land diameter, B = groove diameter
Closeup of barrel throat area. The chamber is to the left, and the muzzle is to the right. The freebore (cyan) and leade (dark grey) transition into rifled bore (pale grey), and the comparison between freebore diameter vs. rifling groove and land diameter.

The bore is the hollow internal

motion while travelling down the bore is referred to as its internal ballistics
.

Most modern firearms (except

attitude and trajectory 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 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.

Muzzle

Rheinmetall 120 mm smoothbore tank gun (seen from the muzzle) of a Leopard 2A4
SIG 550 rifle, equipped with a birdcage-type flash suppressor
Various types of shotgun chokes
Muzzle blast modulated by an A2-style flash suppressor

The muzzle is the front end of a barrel from which the projectile will exit.[11] Precise machining 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.[11]

The rapid expansion of propellant gases at the muzzle during firing also produce a powerful

suppressors (and even muzzle shrouds) can be used to reduce the blast noise intensity
felt by nearby personnel.

Barrel components
Chamber
Chamber
Bore
Bore
Muzzle
Muzzle

See also

Production steps in the cold-hammer forging process to produce the barrels for a double-barrelled shotgun

References

Bibliography

  • Quertermous, Russell C.; Quertermous, Steven C. (1981). Modern Guns (Revised 3rd ed.). Paducah, Kentucky: Collector Books. .