A revolver is a repeating handgun with at least one barrel and a revolving cylinder containing multiple chambers (each holding a single cartridge) for firing. Because most revolver models hold six cartridges before needing to be reloaded, revolvers are commonly called six shooters or sixguns.[1] Due to their rotating cylinder mechanism, they may also be called wheel guns. Before firing, cocking the revolver's hammer partially rotates the cylinder, indexing one of the cylinder chambers into alignment with the barrel, allowing the bullet to be fired through the bore. By sequentially rotating through each chamber, the revolver allows the user to fire multiple times until having to reload the gun, unlike older single-shot firearms that had to be reloaded after each.