Chamber (firearms)

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A cartridge being pushed into the chamber of a Springfield M1903. USMC-120801-M-VG714-002.jpg
A cartridge being pushed into the chamber of a Springfield M1903.

In firearms, the chamber is the cavity at the back end of a breechloader's barrel or cylinder, where the cartridge is inserted before being fired. The rear opening of the chamber is the breech, and is sealed by the breechblock or the bolt. [1] [2]



Rifles and pistols generally have a single chamber integral to their barrels, but revolvers have multiple chambers in their cylinder, and no chamber in their barrel. Thus, rifles and pistols can usually still be fired with the magazine removed as long as a cartridge is inserted into the chamber, while a revolver cannot be fired at all with its cylinder swung out.[ citation needed ]

Chambers of a revolver's cylinder Taurus 627-KLM 357MAG 008.jpg
Chambers of a revolver's cylinder

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, lever-action, bolt action, or automatic action 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). [3]

In firearms design or modification, "chambering" is fitting a weapon's chamber for a particular caliber or round, [4] 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. [2]


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. [5] [6] [7] Such imperfections in chamber may be produced in the manufacturing process or through extensive use. [8] Such chamber marks are even more pronounced on substandard firearms or when firing a from an undersized chamber. [5]

In recent years there has been a push to automate this process via the use of automated firearms databases. [9] Ballistics identification has also seen the development of microstamping technology which purposefully creates chamber marks through engravings on the firing pin and breech face. [10]


  1. Brown, Edmund G. (2009). Handgun Safety Certificate. West Sacramento, California: California Department of Justice. p. 52.
  2. 1 2 Walker, Robert E. (2013-03-21). Cartridges and Firearm Identification. CRC Press. ISBN   978-1-4665-8881-3.
  3. Henshaw, Thomas (1993). The History of Winchester Firearms 1866-1992. Winchester Press. ISBN   978-0-8329-0503-2.
  4. Ramientas, Mike (2020-08-18). ".25-06 Remington vs. .243 Winchester: The Better Overbore -". Gun News Daily. Retrieved 2020-09-01.
  5. 1 2 Sinha, J. K. (2014-11-07). Forensic Investigation of Unusual Firearms: Ballistic and Medico-Legal Evidence. Taylor & Francis. ISBN   978-1-4665-7137-2.
  6. Monturo, Chris (2019-06-15). Forensic Firearm Examination. Elsevier Science. ISBN   978-0-12-814540-1.
  7. Siegel, Jay A.; Mirakovits, Kathy (2015-12-01). Forensic Science: The Basics, Third Edition. Taylor & Francis. ISBN   978-1-4822-5337-5.
  8. Wheeler, Barbara; Wilson, Lori J. (2011-08-10). Practical Forensic Microscopy: A Laboratory Manual. John Wiley & Sons. ISBN   978-1-119-96557-2.
  9. "Mission". Retrieved 2020-09-01.
  10. Page, Douglas (January 1, 2008). "Microstamping calls the shots: a revolutionary gun identification technology finds favor and foes". Vol 35, Issue 1. Law Enforcement Technology. Retrieved 2020-09-02.

See also

Related Research Articles

Firearm Gun for an individual

A firearm is any type of gun designed to be readily carried and used by an individual. The term is legally defined further in different countries.

Machine gun Sustained fully-automatic firearm

A machine gun is an auto-firing, rifled long-barrel autoloading firearm designed for sustained direct fire with fully powered cartridges. Other automatic firearms such as assault rifles and automatic rifles are typically designed more for firing short bursts rather than continuous firepower, and not considered machine guns. Squad automatic weapons, which fire the same cartridge used by the other riflemen from the same combat unit, are functionally light machine guns though not called so. Submachine guns, which are capable of continuous rapid fire but using handgun cartridges, are also not technically regarded as true machine guns.

Revolver Type of handgun that has a cylinder

A revolver is a repeating handgun that has at least one barrel and uses a revolving cylinder containing multiple chambers for firing. Before firing a round, cocking the hammer partially rotates the cylinder, indexing one of the cylinder chambers into alignment with the barrel, allowing the bullet to be fired through the bore. The hammer cocking can be achieved by either the user manually pulling the hammer back, via internal linkage relaying a rearward movement of the trigger, or both. By sequentially rotating through each chamber, the revolver allows the user to fire multiple times until having to reload the gun, unlike older single-shot firearms that had to be reloaded after each shot.


Single-shot firearms are firearms that hold only a single round of ammunition, and must be reloaded manually after every shot. The history of firearms began with single-shot designs, then multi-barreled designs appeared, and eventually many centuries passed before multi-shot repeater designs became commonplace.

Cartridge (firearms) Ammunition consisting of a casing, projectile, propellant and primer

A cartridge or a round is a type of pre-assembled firearm ammunition packaging a projectile, a propellant substance and an ignition device (primer) within a metallic, paper, or plastic case that is precisely made to fit within the barrel chamber of a breechloading gun, for the practical purpose of convenient transportation and handling during shooting. Although in popular usage the term "bullet" is often informally used to refer to a complete cartridge, it is correctly used only to refer to the projectile.

Action (firearms) Functional mechanism of breech-loading

In firearms terminology, an action is the functional mechanism of a breech-loading firearm that handles the ammunition cartridges, or the method by which that mechanism works. Actions are technically not present on muzzleloaders, as all those are single-shot firearms with a closed off breech with the powder and projectile manually loaded from the muzzle. Instead, the muzzleloader ignition mechanism is referred to as the lock.

Semi-automatic firearm

A semi-automatic firearm, also called a self-loading or autoloading firearm, is a repeating firearm whose action mechanism automatically loads a following round of cartridge into the chamber (self-loading) and prepares it for subsequent firing, but requires the shooter to manually actuate the trigger in order to discharge each shot. Typically, this involves the weapon's action utilizing the excess energy released during the preceding shot to unlock and move the bolt, extracting and ejecting the spent cartridge case from the chamber, re-cocking the firing mechanism, and loading a new cartridge into the firing chamber, all without input from the user. To fire again, however, the user must actively release the trigger, allow it to "reset", before pulling the trigger again to fire off the next round. As a result, each trigger-pull only discharges a single round from a semi-automatic weapon, as opposed to a fully automatic weapon, which will shoot continuously as long as the ammunition is replete and the trigger is kept depressed.

Semi-automatic pistol Type of pistol

A semi-automatic pistol is a type of repeating single-chamber handgun (pistol) that automatically cycles its action to insert the subsequent cartridge into the chamber (self-loading), but requires manual actuation of the trigger to actually discharge the following shot. As a result, only one round of ammunition is fired each time the trigger is pulled, as the pistol's fire control group disconnects the trigger mechanism from the firing pin/striker until the trigger has been released and reset.

A repeating rifle is a single-barreled rifle capable of repeated discharges between each ammunition reloads. This is typically achieved by having multiple cartridges stored in a magazine and then fed individually into the chamber by a reciprocating bolt, via either a manual or automatic action mechanism, while the act of chambering the round typically also recocks the hammer/striker for the following shot. In common usage, the term "repeating rifle" most often refers specifically to manual repeating rifles, as opposed to self-loading rifles, which use the recoil and/or blowback of the previous shot to cycle the action and load the next round, even though all self-loading firearms are technically a subcategory of repeating firearms.

Gun barrel Firearm component which guides the projectile during acceleration

A gun barrel is a crucial part of gun-type ranged weapons such as small firearms, artillery pieces and air guns. 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 or millimetres.

Blowback is a system of operation for self-loading firearms that obtains energy from the motion of the cartridge case as it is pushed to the rear by expanding gas created by the ignition of the propellant charge.

Automatic revolver

An automatic revolver is a revolver that uses the energy of firing for cocking the hammer and revolving the cylinder, rather than using manual operations to perform these actions. Despite the name "automatic", such revolvers are actually semi-automatic as the gun will not continue shooting and the shooter still needs to manually actuate the trigger to discharge each shot.

A rim is an external flange that is machined, cast, molded, stamped, or pressed around the bottom of a firearms cartridge. Thus, rimmed cartridges are sometimes called "flanged" cartridges. Almost all cartridges feature an extractor or headspacing rim, in spite of the fact that some cartridges are known as "rimless cartridges". The rim may serve a number of purposes, including providing a lip for the extractor to engage, and sometimes serving to headspace the cartridge.

H&R Firearms Harrington and Richardson firearms manufacturer

H&R 1871, LLC is a manufacturer of firearms under the Harrington & Richardson and New England Firearms trademarks. H&R is a subsidiary of the Remington Outdoor Company. H&R ceased production February 27, 2015.

Break action

Break action is a type of firearm action in which the barrel or barrels are hinged much like a door and rotate perpendicularly to the bore axis to expose the breech and allow loading and unloading of cartridges. A separate operation may be required for the cocking of a hammer to fire the new round. There are many types of break-action firearms; break actions are universal in double-barrelled shotguns, double rifles and combination guns, and are also common in single shot rifles, pistols, and shotguns, and can also be found in flare guns, grenade launchers, air guns and some older revolver designs. They are also known as hinge-action, break-open, break-barrel, break-top, or, on old revolvers, top-break actions.

Antique firearms Firearms older than 20th century

An antique firearm is a term to describe a firearm that was designed and manufactured prior to the beginning of the 20th century. Although the exact definition of what constitutes an "antique firearm" varies between countries, the advent of smokeless powder or the start of the Boer War are often used as cut-off dates. Antique firearms are usually collected because of their historical interest and/or their monetary value.

Cylinder (firearms) The cylindrical, rotating part of a revolver containing multiple chambers, each of which is capable of holding a single cartridge.

In firearms, the cylinder is the cylindrical, rotating part of a revolver containing multiple chambers, each of which is capable of holding a single cartridge. The cylinder rotates (revolves) around a central axis in the revolver's action to sequentially align each individual chamber with the barrel bore for repeated firing. Each time the gun is cocked, the cylinder indexes by one chamber. Serving the same function as a rotary magazine, the cylinder stores ammunitions within the revolver and allows it to fire multiple times before needing to reload.

The following are terms related to firearms and ammunition topics.

Chiappa Firearms, Armi Sport di Chiappa, is an Italian firearms manufacturing company based in Brescia. It was founded in 1958 by Ezechiele Chiappa as Armi Sport. Total unit production is around 60,000 per year. Its U.S. headquarters are in Dayton, Ohio.

Repeating firearm

A repeating firearm is any firearm, either a handgun or a long gun, that is capable of repeated firing before needing to manually reload new ammunition into the gun. These firearms are breechloading by nature. Different to the preceding single-shot firearms, a repeating firearm can store multiple cartridges inside a magazine, a cylinder or a belt, and uses a moving action to manipulate each of these cartridges into and out of battery position, allowing the gun to discharge numerous times in relatively quick succession before a manual ammunition reload is needed.