Mr. McCall enlightens us: Well, I have to disagree with that.  Best result for a shooting is for your largish caliber round to give up all its energy in the body and not come out.  Better hydrostatic shock effects that way, everything else being equal. Fred, you are a victim of a widely held, but false, belief. Then so was the professor who taught me incompressible flow. There is no such thing as hydrostatic shock from a pistol bullet. A .45 ACP has about the same kinetic energy as a fastball (run the numbers yourself), which rarely kill batters, even when hitting one in the head. Except for the brain and the liver, human tissue is very flexible material, and its being stretched and released causes no more damage than a minor bruise. Maybe you should study incompressible flow.  Fluid mechanics is useful for  lot more than just aerodynamics, you know.  You've also overlooked what happens when a bullet hits bone. <preposterous Feynman mode What's the speed of sound in the human body? What are the velocities of US Civil war and modern day bullets in the human body?? </preposterous Feynman mode cMAD <- I need to be careful with that Feynman mode. Last time I used it I was REMARKABLY wrong.

You've also overlooked what happens when a bullet hits bone. True, but that's not a hydrostatic shock issue: more like spalling.

I have to compliment your knowledge of weapons, Mr. Adam. It's a hobby. One that helped me get my current job...

</preposterous Feynman mode Oh, don't stop now!  I like Feynman George

:There is no such thing as hydrostatic shock from a pistol bullet. A .45 ACP has :about the same kinetic energy as a fastball (run the numbers yourself), which :rarely kill batters, even when hitting one in the head. Except for the brain :and the liver, human tissue is very flexible material, and its being stretched :and released causes no more damage than a minor bruise. And if a bullet was the size of a _base_ball so that the impact was spread over that large an area you would be precisely correct. However, consider that one of the factors that keeps us from making lighter, less bulky body armor is that the padding and spreading of the bullet impact is essential.  It's not that a thinner vest cannot stop a bullet.  It can.  However, if the vest is too thin, you have to start worrying about blunt force trauma to internal organs from the bullet impact, which has the possibility of causing lethal trauma even without penetration.

Mr McCall rises to the bait as follows: :There is no such thing as hydrostatic shock from a pistol bullet. A .45 ACP has :about the same kinetic energy as a fastball (run the numbers yourself), which :rarely kill batters, even when hitting one in the head. Except for the brain :and the liver, human tissue is very flexible material, and its being stretched :and released causes no more damage than a minor bruise. And if a bullet was the size of a _base_ball so that the impact was spread over that large an area you would be precisely correct. However, consider that one of the factors that keeps us from making lighter, less bulky body armor is that the padding and spreading of the bullet impact is essential.  It's not that a thinner vest cannot stop a bullet.  It can.  However, if the vest is too thin, you have to start worrying about blunt force trauma to internal organs from the bullet impact, which has the possibility of causing lethal trauma even without penetration. Fred, you are correct insofar as no thin material can reliably stop a bullet of any sort. (Hmm, maybe really hard steel, but that stuff makes crummy shirts), and so when the vest material flexes, some energy transfer is possible. In fact, even the ceramic plates SWAT teams use for center-chest protection can, when hit by a bullet of the .308 Winchester class, transmit enough blunt trauma force to put the heart into lethal fibrillation. (Supposedly some prizefighters have died from this, though I have trouble believing it.) But since pistol bullets inflict injury not by energy transfer, but by physical penetration and direct (crushing) destruction of tissue, the comparison with a _base_ball holds all the water it needs for this discussion. It’s hard to die of a bruise to the abdomen. It’s a lot easier to bleed out from a lacerated spleen. Lensman Hey, Mr. Taliban, tally me munitions. Here they come, and they gonna go boom