Captive bolt pistol - modified version. I'd like yet more modification, the part that gets pushed into the brain should be longer and thicker. The purpose of this thing is to save ammo when making sure the fuckers are dead.
Not really a gun, but bears mentioning. This is only the compressed air canister used by Anton Chigurh in "No Country for Old Men." It powers the Captive Bolt Pistol - a pnuematic gun used to fire a bolt into the brains of cattle before they are slaughtered.