The chamber of a

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 ...

is the cavity at the back end of a breechloading weapon's

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 ...

cylinder A cylinder () 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 infinite ...

, where the

ammunition Ammunition, also known as ammo, is the material fired, scattered, dropped, or detonated from any weapon or weapon system. The term includes both expendable weapons (e.g., bombs, missiles, grenades, land mines), and the component parts of oth ...

is inserted before being fired. The rear opening of the chamber is the breech, and is sealed by the breechblock or the bolt.

Function

The act of ''chambering'' a cartridge means the insertion of a round into the chamber, either manually or through the action of the weapon, e.g.,

pump-action Pump action is a type of manual firearm action that is operated by moving a sliding handguard on the gun's forestock. When shooting, the sliding forend is pulled rearward to eject any expended cartridge (firearms), cartridge and typically to co ...

lever-action The toggle-link action used in the iconic Winchester Model 1873 rifle, one of the most famous lever-action firearms Picture showing a Volcanic Pistol A lever action is a type of action for repeating firearms that uses a manually operated cocki ...

bolt action Bolt action is a type of manual firearm action that is operated by ''directly'' manipulating the turn-bolt via a bolt handle, most commonly placed on the right-hand side of the firearm (as most users are right-handed). The majority of b ...

, or autoloading operation generally in anticipation of firing the weapon, without need to "load" the weapon upon decision to use it (reducing the number of ''actions'' needed to discharge).

Automatic Automatic may refer to: Music Bands * Automatic (Australian band), Australian rock band * Automatic (American band), American rock band * The Automatic, a Welsh alternative rock band Albums * ''Automatic'' (Jack Bruce album), a 1983 el ...

and single-shot pistols (such as Derringers),

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, and

shotgun A shotgun (also known as a scattergun, peppergun, or historically as a fowling piece) is a long gun, long-barreled firearm designed to shoot a straight-walled cartridge (firearms), cartridge known as a shotshell, which discharges numerous small ...

s generally have a single chamber integral to their barrels, but

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 have multiple chambers in their

, and no chamber in their barrel. Thus, pistols, rifles, and shotguns can usually still be fired with the

magazine A magazine is a periodical literature, periodical publication, print or digital, produced on a regular schedule, that contains any of a variety of subject-oriented textual and visual content (media), content forms. Magazines are generally fin ...

removed as long as a cartridge is inserted into the chamber, while a revolver cannot be fired at all with its cylinder swung out or broken open excepting a

hang fire Hang fire is an unexpected delay between the triggering of a firearm and the ignition of the propellant. This failure was common in firearm actions that relied on open primer pans, due to the poor or inconsistent quality of the powder, although ...

or other malfunction. In firearms design or modification, "chambering" is fitting a weapon's chamber for a particular caliber or round, so a Colt Model 1911 is ''chambered'' for .45 ACP or .38 Super, or ''re-chambered'' for .38/.45 Clerke. While the majority of firearms are chambered for one caliber, some are chambered for multiple calibers; however firing an oversized or undersized cartridge can be hazardous.

Fluted chamber

In the barrel chamber, fluting refers to gas relief flutes/grooves used to ease the extraction of cartridges. They may also come in annular and helical forms. Notable firearms using fluted chambers are the roller-delayed blowback

Heckler & Koch G3 The Heckler & Koch G3 () is a selective fire, select-fire battle rifle chambered in 7.62×51mm NATO developed in the 1950s by the German firearms manufacturer Heckler & Koch, in collaboration with the Spanish state-owned firearms manufacturer CE ...

and lever-delayed blowback FAMAS and AA-52. Roller or lever-delayed blowback arms require that the bolt starts moving while the bullet is still in the barrel and the spent case is fully pressurized. Fluting the end of the chamber allows combustion gasses to float the neck and front of the cartridge case providing pressure equalization between the front outer surface of the cartridge case and its interior. The roller-delayed blowback StG 45(M) assault rifle prototypes proved pressure equalization fluting is desirable, since the breech of roller or lever-delayed blowback arms is opened whilst under very high internal cartridge case pressure that presses a spent (bloated) cartridge casing against the chamber walls which can cause significant problems during the cartridge extraction phase. Using traditionally cut (non-fluted) chambers in the StG 45(M) resulted in separated cartridge case heads during testing.

Ported chamber

A barrel chamber with pressure relief ports that allows gas to leak around the cartridge during extraction. Basically, the opposite of a fluted chamber, as it is intended for the cartridge to stick to the chamber wall making a slight delay of extraction. This requires a welded-on sleeve with an annular groove to contain the pressure.

Multi chamber

Mostly used on artillery guns. Multi chambered is where the barrel has a series of chambers to propel the round down the barrel to increase speed and range. The Lymann-Haskell multi chamber gun is an example.

Forensics

The chamber is a key component to the practice of forensic firearm examination. The chamber is known to imprint its surface striations irregularities on the cartridge case, in what are called chamber marks, due to the pressure produced when

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 ...

. Such imperfections in chamber may be produced in the manufacturing process or through extensive use. Such chamber marks are more pronounced on substandard

firearms 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 originated ...

or when firing from an undersized chamber. In recent years there has been a push to automate this process via the use of automated firearms databases.

Ballistics Ballistics is the field of mechanics concerned with the launching, flight behaviour and impact effects of projectiles, especially weapon munitions such as bullets, unguided bombs, rockets and the like; the science or art of designing and acceler ...

identification has also seen the development of microstamping technology which purposefully creates chamber marks through engravings on the

firing pin A firing pin or striker is a part of the firing mechanism of a firearm that impacts the primer in the base of a cartridge and causes it to fire. In firearms terminology, a striker is a particular type of firing pin where a compressed sprin ...

and breech face.

References

External links

Chamber
{{Firearms

Firearms 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 originated ...

Firearm terminology Firearm components