Gun Barrel - Construction

Construction

Modern day gun barrels are sophisticated in their construction and makeup. 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 bullet or shell as it is being pushed out by the expanding gas(es). Early firearms were mostly muzzle loading (loaded from the mouth rather than the breech), which tends to be a slow and complicated procedure, resulting in 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; resulting in a lower muzzle velocity. During the 19th century, effective mechanical locks were invented that allowed loading from the breech while effectively sealing the breech from escaping propellant gases.

Gun barrels are mostly of metal construction. The early Chinese, the inventors of gunpowder, used bamboo, a naturally tubular wood, as the first barrels in gunpowder projectile weapons. Early European guns were made of wrought iron, usually several bands of the metal arranged around circular wrought iron rings and then welded into a hollow cylinder. The Chinese were the first to master cast-iron cannon barrels. Bronze and brass were favoured by gunsmiths, due to their ease of casting and their ability to resist the corrosion created by the combustion of gunpowder. Early cannons were hugely thick for the caliber that they fired. Early manufacturing defects (such as air bubbles trapped in the metal) were key factors in many gun explosions, when the expanding gases became too much for the weak barrel, causing it to rupture and explode in deadly fragments.