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A gel expert explains

Discussion in 'Handguns: General Discussion' started by labnoti, Oct 21, 2019.

  1. 481

    481 Member

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    Another persistent attempt at redirection from the actual topic does not make your failure to provide your proclaimed test results in support "of better correlation of tensile/shear forces in properly prepared wet pack and tissue overall" disappear. You can continue to try to "talk past" what you've offered up-and failed to provide-as evidence in post #251, but it still remains.
     
  2. QED

    QED Member

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    In order to intelligently discuss tensile/shear/compressive force "equivalency" of some matter to tissue, one first has to be familiar with tensile/shear/compressive forces in tissue. The relevant data has been referenced, repeatedly; it's up to you to show evidence of your familiarity with it -- rather than your than bulk modulus/sonic velocity "necessary and sufficient equivalency requirement." If and when you show that you have familiarity with relative magnitudes of forces exerted on a bullet by various "soft" tissues vs. 10% standard ordnance gel, then and only then it might make sense to include comparisons to forces in wet pack.
     
  3. 481

    481 Member

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    Your continued "relocation of the goal line" with post after post of misinformation means that there is no point in further discussion of any of this with you. I am tired of this "shaggy dog" chase, so you win. You may have even made a point in this thread, but it may not be the one that you think you've made. Out.
     
  4. QED

    QED Member

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    Seriously, show evidence that you are familiar with relevant forces in tissue, by having read the referenced material, and no further discussion on this topic may then be in contention... Until then, cheers.
     
  5. C-grunt

    C-grunt Member

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    What are you trying to say here?
     
  6. RetiredUSNChief

    RetiredUSNChief Member

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    I usually end up cutting away all the damaged meat in the area while cleaning the squirrel or rabbit.

    ;););)

    Seriously, the doctors/coroners probably just say "well look at that!" and continue with treatment/autopsy.
     
    481 likes this.
  7. d2wing

    d2wing Member

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    I am pretty sure that deaths by BB or pellet gun is referring to higher powered pellet guns. Not your 290 fps box store Daisy. I have a pellet gun that shoots .22 cal. pellets at 600 fps. There are high pressure pellet large caliber guns that are as powerful as a powder burning rifle.
     
  8. QED

    QED Member

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    Yes indeed, squirrel or rabbit bones have very little chance against even just handgun bullets.
     
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  9. d2wing

    d2wing Member

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    Post withdrawn
     
    Last edited: Dec 13, 2019
  10. Rule3

    Rule3 Member

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    You would have to go back several hundred posts and figure it all out. Perhaps write a brief summary of what has been accomplished other than bantering.
     
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  11. QED

    QED Member

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    What I tried to point out is that 10% standard ordnance gel (never mind that Clear Ballistics stuff and just any "gel" which are so ubiquitously used in posted tests) is not a reliable simulant for human soft tissue (never mind bones) even as far as just penetration and expansion are concerned. Thus, FBI's minimum penetration requirement of 12" in soft tissue will generally not be met with 12" penetration in even 10% standard ordnance gel. It is indeed amusing and amazing to see what irrelevancy has been injected into this topic and this just shows how much confusion there is about this topic.
     
  12. 481

    481 Member

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    It is abundantly clear that you don't know what you don't know.

    Human tissues do have measureable and computable bulk moduli. Here is just one example documenting the mechanical property in human skin, fat, and muscle tissues:
    https://www.google.com/url?sa=t&sou...FjAEegQIBxAB&usg=AOvVaw0t46cqu3ooFAki56SvheGa

    Equation 8 in the linked article relates bulk modulus, mass density and internal sonic velocity using the Newton - Laplace equation rearranged to solve for internal sonic velocity using the mass density and the bulk density of human soft tissues. Took less than 15 seconds of surfin' the 'net to locate the open-source document; there are more sources but it is really not necessary to provide more. In the supplemental equations for the LS-DYNA constitutive EoS for 10% gelatin, or any other material, it matters.
     
    Last edited: Dec 13, 2019
  13. QED

    QED Member

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    Perhaps another point of clarification is in order. As implied by my comment about importance of gel disruption overall and not just the length of the wound track which becomes less than bullet diameter wide as the bullet slows down, it's because non-inertial forces in 10% ordnance gel are generally less than those in many tissues (gel typically has different mechanical properties than tissue). Hence, as long as inertial forces are overcome by a bullet in 10% ordnance gel (along with non-inertial of course) there is then confidence of such bullet penetrating at least as much in "soft" tissue -- otherwise the bullet in tissue could be stopped at any point whereas it could continue penetrating significantly past "inertial forces point" in gel.
     
  14. QED

    QED Member

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    Correct, it's irrelevant. One can determine, theoretically, bullet penetration and expansion in ordnance gel without knowing or caring what bulk modulus or sonic speed in gel is. All that is needed to check the gel for suitability is a weight scale, ruler, and a BB fired into gel at 590 fps. Of course, any material (not vacuum) has a sonic velocity and bulk modulus, but in this discussion those material properties are entirely irrelevant.
     
  15. RetiredUSNChief

    RetiredUSNChief Member

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    Here's another thought:

    If the FBI REALLY thought that ballistic gel ACCURATELY equated to actual distance traveled in human soft tissue, then perhaps their standard penetration requirement would be 6 to 12 inches instead of 12 to 18 inches.

    It seems that the only people who really believe that ballistic gel performance actually equates to identical performance in soft human tissue are people other than the FBI ballistics experts.
     
  16. Kleanbore

    Kleanbore Moderator Staff Member

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  17. Rule3

    Rule3 Member

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    Plus nobody in Florida wears 4 layers of new Denim. Guess they need to test with just a T shirt.:rofl:
     
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  18. QED

    QED Member

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    12" minimum penetration is tissue is not FBI penetration requirement? After their ballistic workshops in late '80s and early '90s (before Fackler's gel was theoretically "validated" by MacPherson) 12" in tissue has been established as a minimum penetration requirement.
     
  19. QED

    QED Member

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    Don't need experts to determine penetration requirement in tissue; a little bit of anatomy knowledge and awareness how large quite a few people are, and possible/probable angles that might come into play is it. The problem is when one says that x bullet penetration in tissue would be met by x penetration in standard gel (not to mention those other "Internet gels").
     
  20. Kleanbore

    Kleanbore Moderator Staff Member

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    No.
     
  21. QED

    QED Member

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    From FBI's Urey Patrick's paper on bullet effectiveness: " It is essential to bear in mind that the single most critical factor remains penetration. While penetration up to 18 inches is preferable, a handgun bullet MUST (his capitalization) reliably penetrate 12 inches of soft tissue."
     
  22. Kleanbore

    Kleanbore Moderator Staff Member

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    That cites the reason for how the requirement became what it is.

    But ammunition developers do not test in soft tissue, nor can they document how ammunition performs in soft tissue.

    The requirement is for minimum and maximum penetration in ballistic gel.

    Thus the statement

    ....is off-base.
     
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  23. QED

    QED Member

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    My above comments were about FBI's minimum penetration requirement of 12" in soft tissue, not about ammunition developers testing practices.
     
  24. Kleanbore

    Kleanbore Moderator Staff Member

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    Without specifying a testing regime, one cannot issue a performance requirement--and the FBI has not issued a minimum penetration requirement for soft tissue.

    Capisce?
     
  25. d2wing

    d2wing Member

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    I have withdrawn my comment and apologize for it. I am a cranky old guy some days.
     
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