By their definition, if an unused bullet is thrown at a brick wall on school property, that is a shooting. It doesn't even need a casing or propellent.
You know you can discharge a bullet by hitting with a rock right? You don't need a gun.
No, you can discharge a cartridge by hitting it with an improvised device. A bullet is just the metal bit in the front of the cartridge that goes flying. Hitting a bullet with a rock does nothing except maybe dent it.