Gun barrel

A gun barrel is the tube, usually metal, through which a deflagration or rapid expansion of gases are released in order to propel a projectile out of the end at a high velocity. Barrels are part of firearms and artillery pieces.

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

Construction

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.

Early firearms were muzzle-loading, with powder, and then shot loaded from the muzzle, 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. During the 19th century effective mechanical locks were invented that sealed a breech-loading weapon against the escape of propellant gases.

Barrel

A barrel, cask, or tun is a hollow cylindrical container, traditionally made of wooden staves bound by wooden or metal hoops. Traditionally, the barrel was a standard size of measure referring to a set capacity or weight of a given commodity. For example, in the UK a barrel of beer refers to a quantity of 36 imperial gallons (160 L; 43 US gal). Wine was shipped in barrels of 119 litres (31 US gal; 26 imp gal).

Modern wooden barrels for wine-making are either made of French common oak (Quercus robur) and white oak (Quercus petraea) or from American white oak (Quercus alba) and have typically these standard sizes: "Bordeaux type" 225 litres (59 US gal; 49 imp gal), "Burgundy type" 228 litres (60 US gal; 50 imp gal) and "Cognac type" 300 litres (79 US gal; 66 imp gal). Modern barrels and casks can also be made of aluminum, stainless steel, and different types of plastic, such as HDPE.

Someone who makes barrels is called a "barrel maker" or cooper. Barrels are only one type of cooperage. Other types include, but are not limited to: buckets, tubs, butter churns, hogsheads, firkins, kegs, kilderkins, tierces, rundlets, puncheons, pipes, tuns, butts, pins, and breakers.

Firearm

A firearm is a portable gun, being a barreled weapon that launches one or more projectiles often driven by the action of an explosive force. The first primitive firearms were invented in 13th century China when the one-person-portable fire lance was combined with projectiles. The technology gradually spread through the rest of East Asia, South Asia, Middle East and then into Europe. In older firearms, the propellant was typically black powder, but modern firearms use smokeless powder or other propellants. Most modern firearms (with the notable exception of smoothbore shotguns) have rifled barrels to impart spin to the projectile for improved flight stability.

Modern firearms are usually described by their caliber (i.e. their bore diameter, this is given in millimeters or inches e.g. 7.5mm, .357) or in the case of shotguns their gauge (e.g. 12 ga.); the type of action employed (muzzle, breech, lever, bolt, pump, revolver, semi-automatic, automatic etc.) together with the usual means of deportment (hand-held or mechanical mounting). They may be further distinguished by reference to the type of barrel used (rifled) and the barrel length (19 inch), the design's primary intended use (e.g. hunting rifle), or the commonly accepted name for a particular variation (e.g. Gatling gun). The word firearms usually is used in a sense restricted to small arms (weapons that can be carried by a single person), whereas the word artillery covers larger gunpowder-fired weapons.