From: hutch@ibeam.intel.com (Steve Hutchison)
Subject: Re: Yet more killing attacks
Organization: Intel Corp., Hillsboro, Oregon
Distribution: intel
Date: Tue, 12 Jan 1993 16:58:58 GMT

dvandom@magnus.acs.ohio-state.edu (Dave Van Domelen) writes:

>In article <1993Jan11.153815.14776@rdg.dec.com> boyes@forty2.enet.dec.com (Mark
> Boyes) writes:
>>Even the biggest, fastest, pointiest bullet can cause a flesh wound?

>Yep.  If a Howitzer blows off your pinky and nothing else, it won't cause much 
>more damage than a .25 blowing off your pinky.  It might even hurt less, if it 
>weren't for the shockwave as it passes.  A projectile has to hit a fleshy bit 
>before hydrostatic shock becomes a factor, and actually fast pointy bullets 
>don't do much unless they hit a really vital part.

To be brief:  Hydrostatic shock is a bogus model.  It only happens when the
bullet hits bone.  I'm appending the relevant article which was posted here
last year (and before and before and ... anyone want to add this to the FAQ?)



In article <850003@hpdml93.HP.COM> rona@hpdml93.HP.COM (ron abramson) writes:
>James Duncan writes:
>
>> 4. Does the ammunition chart make sense to anyone? Do 40+ calibre 
>>    expand much more than other rounds? I am wondering why they have the
>>   special 1.5 damage modifier.
>
>I understand that the army did tests before WWI (or was it the FBI?) in
>which they shot cows with various pistols and examined the damage.  What
>they decided was that larger diameter (calibre) rounds did a lot more 
>internal damage due to a kind of shock wave effect.  Anyway, that was 
>the reason for choosing the .45 calibre as the standard issue firearm.

In an article in, I think, Different Worlds, as part of a review of
Twilight:2000, it mentions and gives a brief overview of a report
published by the Letterman Army Institute titled "Bullet Fragmentation: A
Major Cause of Tissue Disruption". According to the report, most of
the 'commonly accepted facts' about the damage-causing capacities of
bullets are wrong.

Specifics: Almost everything ascribed to hydrostatic shock is bilge.
The passage of the bullet will create a large 'temporary cavity' of
_displaced_ tissue that will close in a period generally not exceeding
ten minutes. The only situations where hydrostatic shock is a factor
in the amount of damage caused by a bullet is where the tissue is
constrained from motion; this is why half-gallon plastic bottles full
of water explode so nicely when shot, as do skulls -- in both cases
the casing (bottle or skull) keeps the contents from deforming (shoot
into a open bucket of water and the results will be unimpressive).

_All_ conceptions about bullet tumble after impact are wrong. _All_
bullets tumble after impact, and the impact consists of _one_
end-for-end swap, so that the bullet exits tailfirst. As a result of
this, and the previous information, the only actual permanent damage
from the bullet path is due to the actual passage of the bullet, and
therefore a long, thin bullet will do more damage than a short, fat
one (the Army tried making a flechette round back in the '50s or '60s,
I believe, but gave it up due to manufacturing problems).

In all of the cases where results corresponding to the classical
theory about hydrostatic shock were found, the bullet fragmented;
examining case reports for combat wounds, bullet fragments or bone
fragments (i.e., the bullet hit a bone, creating fragments) were found
in all cases where previous theories ascribed the damage to
hydrostatic shock.

The reputed effectiveness of the .45 round, it now appears, was due to
other considerations than making a big hole. Being a large, slow slug,
the bullet was less likely to exit the body, making for more efficient
energy transfer (more likely to knock them down). Also, being a large
slug, it had a somewhat higher chance to strike a bone on its way in,
thereby strewing bone fragments along the bullet path.

I'll see if I can dig out the specific reference to the publication;
it can be obtained through the National Technical Information Service
(NTIS), but you need the report number.


	Sean Malloy
	Navy Personnel Research & Development Center
	San Diego, CA 92152-6800
	malloy@nprdc.arpa



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