<P> 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 . </P> <P> 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 . </P>

What part of a gun is the barrel