High Quality Content by WIKIPEDIA articles! A cartridge (also called a round, a shell or ammunition) packages a bullet, propellant (usually either smokeless powder or blackpowder) and a primer within a metallic, paper, or plastic casing that is precisely made to fit within the firing chamber of a firearm. The primer is a small charge of an impact-sensitive or electric-sensitive chemical mixture that can be located at the center of the case head (centerfire ammunition), inside a rim (Rimfire ammunition), or in a projection such as in a pinfire or teat-fire cartridge. Military and commercial producers also make Caseless ammunition. A cartridge without a bullet is called a blank. One that is completely inert (contains no active primer and no propellant) is called a dummy.