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Old September 26, 2012, 03:44 AM   #83
Join Date: February 12, 2001
Location: DFW Area
Posts: 20,919
But I think that the point he's trying to make is that energy as a indicator of a defensive handgun cartridge's effectiveness is not helpful and even counter productive. He is, in essence, responding to what amounts to an obsession with energy, even at typical handgun velocities.
Perhaps. In any event, he swings too far the opposite direction.

Kinetic energy is helpful in understanding terminal ballistics and handgun cartridge effectiveness. It does not, by any means, tell the entire story, and one can certainly be led astray by becoming obsessed with it or by giving it too much consideration when comparing cartridges. However, science does not allow us to discard it, nor is it wise to discount it too much given the obvious correlation between energy, work and damage.
But factors such as sectional density of the bullet, momentum and diameter/expansion of the the bullet and thus the permanent wound cavity are more useful and relevant to trying to predict terminal performance, at least at typical handgun velocities.
The complexities and vagaries of dealing with energy and temporary wound cavities have led some to focus exclusively on other parameters because they allow a more consistent and simpler analysis. However, of necessity, leaving out a factor as basic as kinetic energy leaves their analysis wanting in at least some respects and leads to conclusions that, in some circumstances, can be just as inaccurate and just as unnecessarily limited as those which are generated by people who focus exclusively on energy as a measure of terminal ballistics. Many of the obviously unsupportable statements about discounting temporary cavity and kinetic energy originate from those who have so much invested in these simpler analyses that provide more consistent, though perhaps less accurate, results because they perceive this tactic to be the only way to maintain the credibility of their conclusions.

One very simple example--the list provided as being more useful than energy includes expansion. However, expansion is more closely related to energy than any of the other listed parameters since it is evidence of work done on the projectile and that work is a function of impact energy. Ultimately, energy plays at least some part in nearly every aspect of terminal ballistics--an important part in some respects and under certain circumstances and perhaps a trivial part in other respects and under another set of circumstances.

A list of the "ABCs" of terminal ballistics is just as incomplete without kinetic energy as it would be if one excluded momentum or velocity, and it's not possible to fully understand the topic without understanding how it's affected by kinetic energy. I'm not saying anyone does fully understand the topic--I'm just saying that kinetic energy is one of the basic building blocks of terminal ballistics and any house built without it is incomplete.
There's a significant difference between the physiology of injury from blunt force trauma and injury from a penetrating wound.
It's just as true to say that there's a significant difference between the physiology of a penetrating wound and a wound caused by a high velocity projectile.

The reason both statements are true is that a wound from a high velocity projectile incorporates aspects of both penetrating wounds and blunt force trauma.

In fact, temporary wound cavity is an excellent analog for blunt force trauma. If one is hit in an area containing or composed of brittle or inelastic tissue, it can be catastrophic. If one is hit in an area that is largely made up of elastic tissue, there may be little effect other than pain.

If one completely ignores kinetic energy and temporary cavity, one ignores one of the two main components of high velocity projectile injuries. It's certainly true that the circumstances of a particular situation may dramatically emphasize one of the two aspects over the other, but neither one is ever completely absent, except, perhaps, when effective body armor is involved and there is no penetration.
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