The device used in "No Country for Old Men" is called a Bolt Gun: http://en.wikipedia.org/wiki/Captive_bolt_pistol http://en.wikipedia.org/wiki/Captive_bolt_pi

The device used in "No Country for Old Men" is called a Bolt Gun: http://en.wikipedia.org/wiki/Captive_bolt_pistol http://en.wikipedia.org/wiki/Captive_bolt_pistol It is routinely used to stun/kill various livestock in slaughterhouses... In this case it was a pneumatic bolt gun and probably something that they made from scratch for the film...