CASE (A.K.A. BRASS)
Cases can be called brass, empties, shells, reloading brass, spent cases or brass cases. The case is generally made of brass, steel or aluminum designed to contain the powder charge and the primer. Centerfire cases include all pistol and rifle cartridges that have primers in the center of the cartridge base. Rimfire cases have the primer located in the rim of the case. Brass- and nickel-plated brass are reloadable while rimfire, steel and aluminum cases that are not reloadable.
POWDER
The term for any chemical compound, normally gunpowder, used to propel the bullet out of the barrel when ignited by a struck primer. Powder is commonly found in two varieties, smokeless and black. Smokeless powder is found in modern ammunition and has a significantly reduced smoke signature. Black powder on the other hand is very smoky and can be corrosive.