At the very end of the 2007 movie Live Free or Die Hard, Bruce Willis gets shot in the shoulder. Towards the end of the fight, the gun is placed in the same spot where he was shot. Bruce pulls the trigger and the bullet enters and exits through the same holes (that were in his shoulder) killing the guy behind him. I would like to know if a bullet can actually enter though the same entry point and exit in the same spot without causing any more damage to you and killing the person behind you who is holding the gun.

I recon it is possible to fire a bullet through the same hole and kill a person behind, but it would be an extrememly difficult and unlikely shot.

The issues I forsee;

* For one, the bullet would need to be fired at precisely the same angle for it to pass through the ready made wound. A slight deviation would send the bullet in a different trajectory or perhaps lodge against previously missed bones and muscle.

* There's also the fact that although a bullet has already passed through him, the wound will have begun to collapse and fill with fluids making the passage of the next bullet meet at least some resistence.

* There would almost certainly be considerable additional damage (probably fatal), from the second shot. The expanding gases from the barrel would erupt and discharge inside the body cavity. This would cause enormous tissue damage and probably collapse the lung. There would also be additional fragmentation damage. I believe that if the first shot was survivable, then the second shot fired at such close range would almost certainly kill Bruce Willis.

* The bullet would lose some velocity as it passes through and out of the previous wound but would probably not have mushroomed yet. So I think it would penetrate far enough into the person behind so as to cause a potentially fatal wound.

So yes, I believe you could kill someone with the technique used, but at the expense of not one, but two lifes.

Xenomorph is largely correct - also bear in mind that when studying wound ballistics, the tissue & organ damage caused by the projectile is actually quite minor - there are any number of places in the body where you could drill a 9mm hole through with minimal damage. What really causes the damage is the shockwave caused by the high-speed displacement of the projectile passing through tissue - the body, as we know, is 97% water, and the science of fluid dynamics is what governs the dispersion of the shockwave through tissue. And, as xenomorph states, with a contact wound, that effect is magnified by the gaseous emmision from the weapon as well. I am an ex-soldier and I have seen plenty of wounds where major organs were damaged, and even bones broken, which were not impacted by the projectile.

One must also consider that the actual hole made by the original bullet would be very small, and the elasticity of the skin would mean that it would close over almost immediately. I have also seen any number of gunshot wounds from high-velocity sub-.50 inch projectiles with virtually no bleeding - unless a major artery is hit, therefore causing internal pressure in the wound, almost no hole is left for anything to leak out of. Which begs the question, how could Willis be sure he was actually shooting through the same hole?

I also do not believe such a second shot would be survivable.