A revolver is a repeating handgun that has at least one barrel and uses a revolving cylinder containing multiple chambers for firing. Because most revolver models hold up to six cartridges, before needing to be reloaded, revolvers are commonly called six shooters or sixguns. Due to their rotating cylinder mechanism, they may also be called wheel guns.

A gun barrel is a crucial part of gun-type 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(es) is used to propel a projectile out of the front end (muzzle) 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.