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Thread: TSX hydro-static shock

  1. #1

    Default TSX hydro-static shock

    A little while back there was some discussion about hydro-static shock/temporary wound cavity. In other words, the "shock-wave" produced in soft tissue when a bullet passes through it at high velocity. This temporary shock-cavity is significantly larger than the caliber of the bullet. For those of you who place a lot of stock this phenom. (as I do)- this question is for you:
    Do the petals of the TSX produce this effect as well as the traditional "mushroom" of a bonded lead bullet? It seems to me that a traditional mushroom pushing its way through soft tissue would send out a greater shockwave than thin petals would. What do you think?

  2. #2
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    Most of the hydrastatic shock is caused by the velocity and it requires a somewhat high velocity to achieve this. From the medical books I had a privledge to read it is most apparent above 2,800 FPS. This is one reason why the .223 was picked for a military round and the bullet itself is somewhat designed to tumble. Sometimes people confuse hydrastatic shock with secondary missles (pieces of the bullet and/or bones) that fly off in all directions when the bullet hits. Hydrastatic shock is bascially the bullet hits with the necessary velocity and then the surrounding tiissue can not expand quickly enough to accomandate it, thus the "explosion". Fascinating reading to be sure and I am certaintly not an expert on this.
    Most importantly, the velocity the bullet is traveling when it hits flesh is the primary factor of how much tissue is destroyed assumming the bullet holds together.
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    Here is what Ken Howell has to say on the matter.

    The term hydrostatic seems to be a term born of ignorance and the love of many for all the extra "syllabobbables" that they can tack onto a good word. The phenomenon that it refers-to (ignoring the alleged effect for the moment) is simple hydraulics, with the applied force and pressure being dynamic rather than static.

    The basic physics principle that's involved is simple and well known — pressure applied to a liquid (incompressible) is applied by that liquid, equally and undiminished, over its entire surface. This principle is what operates hydraulic jacks, hydraulic lifts, all hydraulic cylinders — a hydraulic piston applies a force to a small surface of the fluid, and the pressure (force per square inch) is applied equally and undiminished to all surfaces of the fluid.

    That's why a can of water, struck by a fast bullet, becomes so quickly and dramatically a mangled twist of metal and a cloud of spray. The bullet is a rapidly moving hydraulic piston, and the water — incompressible — applies the pressure of the bullet's impact to all surfaces of the water (dynamically, not statically).

    A heart shot can devastate the heart if it strikes a ventricle at the moment when it's turgid with blood but be only slowly fatal by causing an empty ventricle to leak blood slowly from a bullet hole. In a similar but unrelated way, a pin ***** pops an inflated balloon but simply makes a leak hole in a flaccid balloon.

    My uncle — an Army surgeon — told me of "superficial" but fatal wounds in soldiers' thighs that must've struck the femoral arteries during one precise instant when those arteries were turgid with pulses of blood. Apparently, the essentially instantaneous hydraulic transfer of the bullet's impact pressure devastated the heart as well as the artery and was thus immediately fatal. This was — is — by no means typical of bullet wounds in the thigh, obviously, including thigh wounds that penetrate the femoral artery.

    No one can time or place a shot so as to be certain to get this instantaneously fatal effect, and the concept of "-static" is nonsense anyway. I use the term hydraulic shock for the known phenomenon of basic physics, but I've never believed it to be the magically instantaneous killer that so many theorists have claimed for it. Observations and experience are usually better witnesses to actual real-world facts and phenomena than opinion and theory are.

    Blood (a liquid) isn't compressible. Air (not a liquid) is compressible. A significant distinction.

    … because they're legitimate terms that are useful in other discussions of how fluids flow. Besides, I didn't say or mean to imply "that there is no honest need for differentiating hydrostatic from hydrodynamic" — only that the phenomenon that concerns us here is simple enough and easy enough to understand without 'em.

    Differentiating hydrostatic from hydrodynamic is beside the point in the matter of understanding what happens when a bullet hits a liquid. The bullet is obviously moving (so it's dynamic, not static), which means that tacking -static onto the root hydro- is a misuse of words, anyway.

    That's where the confusion really starts, I think — and clouded secondarily by the misapplied "-static." The crux of the matter is more that the body liquids are incompressible, not so much that they can't move "out of the way" fast enough to absorb the bullet's impact energy. In the theory that has so long been mislabeled "-static," the idea was supposed to be the instantaneous transfer of shock, not the absorption of energy. The original claims and references rested on the notion that I've tried to explain above, but without explaining it so much as alluding to it.

    Those old claims and theories rested on the obviously fallacious notion that an animal was analagous to a can of water. If it were, the old claims would "hold water." Clearly, the physiology of animals is in no way close to the make-up of a can of water — so whether we call it "dynamic" or "static" or even "philosophical" or "black magic" is irrelevant in the final analysis. It's a fine theory that the real world just doesn't go along with.

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