Basic Components of Ammunition
The basic components of ammunition are the case, primer, powder, and projectile(s). Shotshells have an additional component called wad.
Case/Hull: Container that holds all the other ammunition components together. It is usually made of brass, steel, copper, paper, or plastic.
Primer: Explosive chemical compound that ignites the gunpowder when struck by a firing pin. Primer may be placed either in the rim of the case (rimfire) or in the center of the base of the case (centerfire).
Gunpowder: Chemical mixture that burns rapidly and converts to an expanding gas when ignited. Modern smokeless powder will burn slowly when ignited in the open (outside of the case). Black powder is less stable and can be explosive when impacted or ignited in the open.
Projectile: Object(s) expelled from the barrel. A bullet is a projectile fired through a rifle or handgun barrel. A slug is a solid projectile fired through a shotgun barrel. Shot is a group of pellets fired through a shotgun barrel.
Wad: A seal and/or shot container made of paper or plastic separating the powder from the slug or shot in a shot shell. The wad prevents gas from escaping through the shot and holds the shot together as it passes through the barrel.