Michael Courtney
Member
"Energy transfer" is really NOT a significant factor. Why? Because if the bullet is breaking apart, that energy is being transferred to the destruction of the bullet, not to the target. Same with expansion.
Only a small fraction (< 10% in most cases) of the bullet's kinetic energy is absorbed by expansion and/or fragmentation of the bullet.
The retarding force between bullet and tissue is exactly equal to the local rate of the projectile's kinetic energy loss. This is the force that is responsible for indirect tissue injuries incapacitating effects.
A bullet that loses 40% of its mass to fragmentation will have a peak retarding force roughly 40% larger than a comparable bullet (same impact energy and penetration depth) that does not fragment. This significant increase in retarding force is much larger than the relatively insignificant differences in energy required to deform/fragment the bullets.
What is important is the wound channel. how big it is and what it destroys.
No one debates whether or not the wound channel is important. The question is whether or not the wound channel is the only thing that is important. There is a growing body of scientific evidence that provides compelling support for the idea that distant effects also play an important role.
It isn't the "transfer of energy" that creates tissue destruction.
The Textbook of Military Medicine cites plenty of research documenting the importance of local transfer of energy in tissue destruction. Are you somehow more enlightened by the MDs and PhD's who conducted the original research and the US Military surgeons who reviewed the material and included it in the Textbook of Military Medicine?
Also, flat bullets have greater impact effect than spitzer bullets. So you can get a "splash" from a flat or blunt bullet at less velocity than you could with a pointed bullet.
Expansion turns a spitzer bullet into a more blunt projectile. Tumbling in tissue also gives a blunter profile to a spitzer bullet.
I've always heard that with the spitzer type bullets, you need a velocity of 2600 fps to actually get an effective hydraulic reaction. Anything less than that would require a blunter bullet.
The effectiveness of tissue effects needs to be parameterized in terms of the projectile's loss of kinetic energy rather than velocity. There are some excellent graphs that describe this in the Textbook of Military Medicine. Remote effects have been documented for AK47 bullets (< 2600 FPS, spitzer bullets) that apparently did not tumble.
I would estimate that distant effects are likely for bullets that lose more than 100 ft-lbs of energy in an inch of penetration if it occurs sufficiently close to vital organs. There are certainly plenty of documented examples suggesting this criteria is reasonable.
Michael Courtney