The New York Post:
A prop gun — a firearm filled with blanks and used in the film industry to mimic live ammunition — may sound harmless, but it can be dangerous and even deadly, as was the case on the set of Alec Baldwin’s new movie “Rust” this week.
Gunfire in movies appears very convincing because blanks used to imitate live ammo are basically modified real bullets.
Live rounds consist of a cartridge that contains propellant powder, which is ignited when the gun is fired and propels the bullet — the actual projectile at the top of the shell — out of the barrel.
But rather than using metal projectiles, blanks contain materials such as cotton, paper or wax wadding attached to the front to imitate live-fire — including a loud bang, muzzle flash and a realistic recoil.
Still, even without real metal projectiles, blanks can be very dangerous, the BBC notes, because some filmmakers use extra powder to make the superheated gas discharge even more realistic.
The wadding used to hold the gunpowder in place instead of a bullet gets expelled when the trigger is pulled and can cause serious damage – and even death, as was the case when actor Jon-Erik Hexum was killed in 1984.