Recono
Well I know what I saw and I wasn't smoking wacky weed or drinking at the time. You don't disagree with the results of Kent's experiment, but you think there is no way a roo was knocked over (maybe I gave the wrong impression with "flipped" it didn't get lifted off the ground or fly through the air). O.K. think what you like but I know what I saw and I'm convinced it didn't jump.
FYI The roo I shot would have weighed less than a 100lbs and stood about 4". This is about average size for a female eastern grey. Big males can go 180lbs and about 6".

Have a good weekend

416,

I believe I understand what you are saying, and I certainly don't doubt that you saw what you saw. What I doubt is the explanation. Maybe some of our medical friends can help. Although perhaps only you will be able to judge whether it is relevant, you might find it interesting to read what "Doctari" Robertson says in The Perfect Shot about some of the things even half-butchered crocodiles have been known to do.

I guess I trust my limited understanding of physics more than my limited understanding of physiology.

More grist for the mill! http://www.gsgroup.co.za/faqdesign.html There is a picture right at the bottom of the page that may be of interest.

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Gerard Schultz
GS Custom Bullets

Gerard, does this same concept apply to a soft round nose bullet once it has deformed and flattened out? I have 440 grain soft points that I recovered that measure almost an inch in diameter and are flat! That is disrupting alot more tissue than a 375 flat pointed solid isn't it?

Kent

Kent,
It depends entirely on the shapes achieved and the speeds involved when penetrating the body. The following is well described in "Bullet Penetration" by Duncan McPherson. Don't shoot me, I am only the messenger

1. Stagnation pressure at the nose of the bullet causes deformation of the bullet and tissue.
2. Stagnation pressure develops only at areas that are at a right angle to the direction of travel and drops off quickly on any surface angled away from the direction of travel.
3. Stagnation pressure increases disproporsionally to increases in speed. At 2200 fps it is 32600 psi and at 2600 fps it is 45500 psi.
4. A cup shape at the nose of the bullet delivers the same stagnation pressure as a vertical face.
5. Stagnation pressure is what snaps the tissue away from the centerline of the bullet and peripherally away from the bullet path.

Bearing the above in mind, it supports what we have seen in the shooting of animals with various shapes of bullet: A cylinder shape with a vertical face, cuts a more disruptive permanent wound channel than any other shape. Further to that, even a 100 fps increase will significantly increase the temporary wound channel, causing it to contribute to the final size of the permanent wound channel. In practise we have seen that a 270 gr flat nose 375 at 2900 fps bullet will deliver a similar size wound channel to a 500 gr jacketed soft from a 458 Lott at 2350 fps and go deeper. Even a 265 gr HV from a 378 Weatherby, that loses the petals entirely and deforms to a nice cylinder weighing 220 gr, will do more damage than a standard soft from a Lott. The reason, purely and simply, is the shape presented to the direction of travel through the body. Consider also that the reliability of a flat nosed bullet, or a bullet that reliably changes to a flat nosed bullet, is higher because it is a less complex mechanism. The variables involved in deforming to complex shapes, with multi-metal bullets, introduces unpredictability into the results and that is what makes these discussions so interesting.

Fixed my spelling.
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Gerard Schultz
GS Custom Bullets

[This message has been edited by Gerard (edited 02-16-2002).]

The stagnation pressure is the pressure that results from the complete transfer of the velocity of the bullet into pressure. Strictly speaking the stagnation pressure is only seen at an infinitessimal point at the exact centerpoint of the bullet nose and has absolutely nothing to do with the shape of the bullet, either in terms of its magnitude or extent. It depends only on the velocity of the bullet and is given by P = density / 2 x velocity^2, where the density is that of the fluid body.

Now the pressure flow field generated by the passage of the bullet obviously extends far away from the centerpoint of the nose and pressure falls off exponentially (cube law) as the energy of motion is distributed over a larger and larger volume. The shape of the bullet is vital to the way in which this flow field is expressed. A broad flat nose will create a sharp angle of departure from the bullet, whereas a (stable) pointed shape will allow a much more graceful angle of departure from the stagnation point. This also drives the near field pressures. A flat point shape will result in higher near field pressures and more likelihood of flow stresses in tissues that exceed the elastic limits.