page_title: Gun barrel
section_title: Chamber
hierarchical_section_title: Gun barrel / Components / Chamber
caption_attribution_description: English: Fred Gowen, a veteran from the battle of Hue City, 1968, during the Vietnam War, waits with a round in the chamber for his target to reappear, during the Vintage Sniper Rifle Matches, Aug., 1, 2012 aboard Camp Perry, Ohio. When the targets appeared competitors had 20 seconds to adjust their sites and send a round down range before the targets would disappear into the pits and reappear in 20 seconds for another shot. Competitors shot 10 rounds at the 300 and 10 rounds at the 600 in this manner.
context_page_description: 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 is ifsfe w propel it out of the front end 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.
  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 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.
context_section_description: 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 (rifles, 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 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 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 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.
  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 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 or model of cartridge.
caption: A cartridge chambered into a Springfield M1903
exif: {"Image Make": "Canon", "Image Model": "Canon EOS 5D Mark II", "Image XResolution": "240", "Image YResolution": "240", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop Lightroom 4.1 (Macintosh)", "Image DateTime": "2012:08:02 15:36:28", "Image ExifOffset": "216", "EXIF ExposureTime": "1/200", "EXIF FNumber": "10", "EXIF ExposureProgram": "Manual", "EXIF ISOSpeedRatings": "200", "EXIF ExifVersion": "0230", "EXIF DateTimeOriginal": "2012:08:01 15:09:43", "EXIF DateTimeDigitized": "2012:08:01 15:09:43", "EXIF ShutterSpeedValue": "477741/62500", "EXIF ApertureValue": "415241/62500", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "5", "EXIF MeteringMode": "Pattern", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "300", "EXIF SubSecTimeOriginal": "56", "EXIF SubSecTimeDigitized": "56", "EXIF FocalPlaneXResolution": "5616000/1459", "EXIF FocalPlaneYResolution": "1872000/479", "EXIF FocalPlaneResolutionUnit": "2", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Manual Exposure", "EXIF WhiteBalance": "Manual", "EXIF SceneCaptureType": "Standard", "EXIF BodySerialNumber": "2321307213", "EXIF LensSpecification": "[28, 300, 0/0, 0/0]", "EXIF LensModel": "EF28-300mm f/3.5-5.6L IS USM"}