Gun barrel

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A gun barrel is a part of firearms and artillery pieces. It is the straight shooting tube, usually made of rigid high-strength metal, through which a deflagration or rapid expansion of high-pressure gases are released in order to propel a projectile out of the end at a high velocity. The hollow interior of the barrel is called the bore.

The first firearms were made at a time when metallurgy was not advanced enough to cast tubes able to withstand the explosive forces of early cannon, so the pipe (often built from staves of metal) needed to be braced periodically along its length, producing an appearance somewhat reminiscent of a storage barrel.[1]


A US 240 mm howitzer in use in 1944

A gun barrel must be able to hold in the expanding gas produced by the propellants to ensure that optimum muzzle velocity is attained by the projectile as it is being pushed out by the expanding gas(es). Modern small arms barrels are made of materials known and tested to withstand the pressures involved. Artillery pieces are made by various techniques providing reliably sufficient strength.[2][3]

Early firearms were muzzle-loading, with the gunpowder and then the shot loaded from the front end (muzzle) of the barrel, capable of only a low rate of fire. Breech loading provided a higher rate of fire, but early breech-loading guns lacked an effective way of sealing the escaping gases that leaked from the back end of the barrel, reducing the available muzzle velocity.[4] During the 19th century effective breechblocks were invented that sealed a breech-loading weapon against the escape of propellant gases.[5]

Gun barrels are usually metal. The early Chinese, the inventors of gunpowder, used bamboo, a naturally tubular stalk, as the first barrels in gunpowder projectile weapons.[6] 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.[7] The Chinese were the first to master cast-iron cannon barrels. 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.[8]

Early cannon barrels were very thick for their caliber. Manufacturing defects such as air bubbles trapped in the metal were common, and key factors in many gun explosions; the defects made the barrel too weak to withstand the pressures of firing, causing it to fragment explosively.[9]


Muzzle of a SIG 550 rifle.

The muzzle is the end of barrel from which the projectile will exit.[10] Precise machining of the muzzle is crucial to accuracy, because it is the last point of contact between the barrel and the projectile. If 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).

In the case of rifled weapons, the contour of a muzzle is designed to keep the rifling safe from damage, so it is commonly recessed or protected by a convex crown, which is sometimes recessed from the outside rim of the muzzle to avoid accidental damage.

When firing a gun, a bright flash is often seen at the muzzle (known as a muzzle flash) and is produced by the hot gases escaping the barrel. The size of the flash depends on various factors such as barrel length, the type and amount of powder used by the cartridge, etc. Flash suppressors are attached to the muzzle of the weapon to diminish these effects.[10]

See also[edit]


  1. ^ A History of Warfare - Keegan, John, Vintage 1993
  2. ^ Weir, William (2005). 50 Weapons That Changed Warfare. Career Press. p. 131. ISBN 978-1-56414-756-1. 
  3. ^ Payne, Craig M. (2006). Principles of Naval Weapon Systems. Naval Institute Press. p. 263. ISBN 978-1-59114-658-2. 
  4. ^ James, Rodney (15 December 2010). The ABCs Of Reloading: The Definitive Guide for Novice to Expert. Iola, Wisconsin: Krause Publications. p. 21. ISBN 1-4402-1787-4. 
  5. ^ Moller, George D. (15 November 2011). American Military Shoulder Arms, Volume III: Flintlock Alterations and Muzzleloading Percussion Shoulder Arms, 1840-1865. UNM Press. pp. 98–99. ISBN 978-0-8263-5002-2. 
  6. ^ "The History of Weapons". 
  7. ^ Lavery, Brian (1987). "The Shape of Guns". The Arming and Fitting of English Ships of War, 1600-1815. Naval Institute Press. pp. 88–90. ISBN 978-0-87021-009-9. 
  8. ^ Goddard, Jolyon (2010). Concise History of Science & Invention: An Illustrated Time Line. National Geographic. p. 92. ISBN 978-1-4262-0544-6. 
  9. ^ Kinard, Jeff (2007). Artillery: An Illustrated History of Its Impact. ABC-CLIO. p. 77. ISBN 978-1-85109-556-8. 
  10. ^ a b Quertermous & Quertermous, pp.429


  • Quertermous, Russell C.; Quertermous, Steven C. (1981). Modern Guns (Revised 3rd ed.). Paducah, Kentucky: Collector Books. ISBN 0-89145-146-3.