When a firearm is fired- The firing pin indents the primer, which ignites the priming compound, sending a flame through the flash hole of the brass, which ignites the powder. The quickly burning powder then creates large amounts of gas that expand the case to seal the chamber and pushes the bullet down the barrel. The now empty brass case is then removed manually or by the action of the firearm.

Anatomy of Ammo | Cartridge Case | The Three Ps | When a Firearm is Fired