Pistol Primers For Sale. Pistol primers are a type of ignition device used in firearms, specifically in handguns. They are used to ignite the gunpowder in the cartridge and propel the bullet out of the barrel. Pistol primers are specifically designed for use in handguns, and are different in size and composition from other types of primers such as large rifle or shotgun primers. The size of pistol primers can vary, with small pistol primers and large pistol primers being the two most common sizes. Pistol Primers For Sale.