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From: andy@Theory.Stanford.EDU (Andy Freeman)
Newsgroups: sci.military
Subject: Re: Using the rifle suited to the previous war?
Message-ID: <1991Jan19.040239.4164@cbnews.att.com>
Date: 19 Jan 91 04:02:39 GMT
References: <1991Jan5.021828.27885@cbnews.att.com> <1991Jan17.054422.29971@cbnews.att.com>
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From: andy@Theory.Stanford.EDU (Andy Freeman)
In article <1991Jan17.054422.29971@cbnews.att.com> !simnet@ssc-vax (Mark R Poulson) writes:
>There are two important areas to consider ballistically. First, wounds are
>usualy much more severe when the bullet strikes its target with a velocity
>greater than 2100 f/s (the speed of sound in water/flesh).

Wound ballistics is a field filled with "common sense" that doesn't
seem to have any relevant supporting evidence.  In particular, there
are lots of plausible mechanisms, shock waves, crushing,
ripping/tearing, temporary/permanent cavity formation, etc, but
only one, the size of the permanent cavity (assuming sufficient
depth) actually seems to correlate with damage in humans.

In particular, temporary cavities, which targets like melons and water
jugs demonstrate vividly, don't actually matter (with the exception of
skin and liver damage, neither organ flexes much, and brain damage,
because the skull doesn't flex).

Much of the confusion comes from reasonable assumptions that aren't
true.  For example, causing twice as much damage to a melon doesn't
mean that more, let alone twice as much, damage will be inflicted on a
human.  (The two targets have very different characteristics, namely
elasticity.)  Even within the same media, things don't always work
out the way you'd expect.  For example, more velocity with the same
bullet doesn't necessarily result in a larger permanent cavity.
(No, I'm not talking about over-penetration, I'm talking about the
observed behavior that excess velocity often results in a much larger
temporary cavity and the same, or smaller, permanent cavity.)

This info comes from the U.S. Army's expert in wound ballistics,
Col Martin Fackler, M.D., at the Presido.

-andy
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