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FBI 12-18" Ballistic Gel Penetration

Discussion in 'General Gun Discussions' started by LookAtYou, Jan 27, 2020.

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  1. LookAtYou

    LookAtYou Member

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    Hi guys, I had a quick question. I was studying the FBI Protocol when it comes to the 10% Ballistic Gel penetration standards, and after digging through multiple websites, I noticed that certain aspects aren't talked about as much, like skin resistance. Do you all no how many inches of gel is equivalent to penetrating through skin (forearm), and exiting the skin (forearm)? I know everyone says that 12" in gel IS NOT 12" in a body, so I was curious as to how much skin played a part in that. I obviously know other things like bone does too.

    Not sure if true, but I've read that penetrating skin (entry) takes equivalent of 2" of gel, and 4" to exit. If this is true, that's a whopping 6" taken off of penetration right there, and maybe 8" if has to penetrate bone (another 2") in the forearm as well. Not to mention the skin and bone of the chest. That might mean by the time you get through an arm, and the bone of chest, that's 12" of penetration already?
     
  2. bdickens

    bdickens Member

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    Doesn't matter.

    Ballistic gelatin is intended to model an average aggregate of human tissue. That's "model," not "duplicate."

    The reason for the 12" - 16" of penetration, I believe, is to ensure that the bullet has a good chance of reaching something vital in the event it has to pass through say, an arm first or at a steep angle.
     
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  3. 94045

    94045 Member

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    Evidence from autopsies indicates that bullets that penetrate 12-18" in 10% ordnance gel that don't exit their intended target penetrate +/- 20% of that distance in soft tissue. I'm guessing the reason for the correlation despite the elasticity of skin is the fact that the gel is formulated to match porcine muscle tissue and the soft tissue in the intended target is not all muscle.

    As far as bone strikes outside of very solid structures such as knuckles I see very little effect in overall penetration in hogs. I think this is because heavy bone strikes usually reduce the size of the mushroom offsetting the loss of momentum. Assuming good expansion and adequate penetration I generally find them just under the hide or in the first layer of fleece (my bullet stop) either way. What I usually see in a bullet that has went through two ribs (both sides) looks more like a cross between a 4LD and bullet barrier test bullet but one that went through all soft tissue looks like a text book gel bullet.

    I have been informed that shooting porcine tissue tells you nothing. Only reconstituted porcine tissue intended to simulate porcine tissue is legitimate.
     
    Last edited: Jan 28, 2020
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  4. jmr40

    jmr40 Member

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    There is no way to predict WHERE a bullet will impact when testing. If a certain bullet will penetrate 12" in gel that isn't a guarantee that it will always penetrate 12" in human flesh. But by keeping the test medium the same a bullet that penetrates 12" in gel will penetrate deeper in human flesh no matter where it hits than the bullet that only penetrates 8" in gel.
     
  5. 94045

    94045 Member

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    I believe we are testing for different things.

    Hold your disbelief for a moment and see it from my point of few.

    You are examining the performance of one bullet against another in a homogenous substance. This is necessary for development and confirmation that a round meets design criteria.

    I'm testing to see if a specific bullet from a specific lot number will consistently expand, give adequate penetration and not over penetrate in a varying environment.

    I really have a hard time relating a given inches in gelatin to penetration after multiple bone strikes through a body. I have yet to find a formula for this.

    I know what happens when a LE40T3 goes through 4LD, a hog skin, muscle tissue, two ribs and both lungs though. (It gives a mushroom that looks like it's been shot into a rock and penetrates roughly 11-13").

    How many inches of gel would be indicative of this? 15"?

    The problem is my results while reasonably repeatable with proper bullet placement sometimes are radically different than gel test. Now wether that means I can't trust the test I read, it's a different lot # or I should ignore results in an actual body (although porcine) in deference to gel I don't know. I just can't imagine someone at the FBI saying it doesn't matter how bad it performs in the field as long as it works in the lab.
     
  6. Shawn Dodson

    Shawn Dodson Member

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    Skin does not offer any addition resistance to bullet entry however unshored skin can offer as much as 4" resistance when a bullet exits, depending on thickness of the skin. Skin on the back is the thickest and bullets are usually found just underneath the skin. Thinner skin on arms offers less resistance to bullet exit because it's thinner. On exit skin stretches then tears, and the flaps of torn skin can be folded back into original position.
     
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  7. 94045

    94045 Member

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    This I can actually agree with that some what although I'm not sure hog skin/hide doesn't provide some detriment to expansion. It does seem to provide a barrier to exit. However my flannel.backstop may make exiting easier. I'm.reluctant to do.away with completely due to lost test rounds.
     
  8. Shawn Dodson

    Shawn Dodson Member

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    There have been several studies to validate the penetration depth observed in properly prepared and calibrated ordnance gelatin compared to penetration depth in the human body. One study, by the late Gene Wolberg, with San Diego PD, showed the average penetration depth in properly prepared and calibrated ordnance gelatin was the same in the human body however the range of penetration depth in the human body was greater. Several other studies by various law enforcement and military groups yielded the same results.
     
    Last edited: Jan 28, 2020
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  9. Shawn Dodson

    Shawn Dodson Member

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    I can see where a thick animal hide can plug a JHP bullet and inhibit expansion.
     
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  10. Shawn Dodson

    Shawn Dodson Member

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    Ordnance gelatin simulates soft tissues only - a "simple" wound.

    Bone from a freshly killed hog can be included with ordnance gelatin to simulate a "complex" wound.
     
  11. 94045

    94045 Member

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    I believe that was the one I saw that only considered bullets that penetrated strickly soft tissue and did not exit. Im not sure you can totally disregard all bullets that over-penetrate and all bullets that strike bone and consider the remaining bullets representative of what happens in the human body versus gel as a whole.

    While the average was longer some bullets under penetrated by 20% in the body some a similar amount over.

    If I am misinterpreting the study parameters I will stand corrected.
     
  12. Shawn Dodson

    Shawn Dodson Member

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    Dr. Martin Facker, who developed the 10% type 250A ordnance gelatin soft tissue simulant protocol and father of modern wound ballistics stated, "The field is the ultimate laboratory."
     
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  13. Shawn Dodson

    Shawn Dodson Member

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    Facker frequently shot anesthetized and freshly euthanized hogs in his wound ballistics laboratory.
     
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  14. 94045

    94045 Member

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    When you only consider bullets that pass through soft tissue and disregard any bullets that exited the body or struck bone I would say the study only equates soft tissue performance with gel and may possibly understate average penetration at that (since no consideration was given to wound track length of exiting rounds).

    I don't think a freshly killed wild pig thorax is a good media for bullet development where you need consistency. I do believe it gives you a better handle on the potential range of penetration and expansion you may see in actual use than a homogenous substance.
     
  15. 94045

    94045 Member

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    Yes but apparently others here don't believe any work not done with ballistic gel is valid.
    Despite it being developed to be a substitute for hogs.
     
  16. Shawn Dodson

    Shawn Dodson Member

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    Ha!
     
  17. 94045

    94045 Member

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    I changed that after you quoted it.
    Decided it was to hyperbolic. Sorry..
    I just have an abundance of wild hog carcasses (it's a never ending battle to keep them under control).

    I don't disagree that gel is a valid media.
    I just don't agree that it's the only valid media to learn something (not necessarily to compare the two).

    I'm going to leave this subject alone now before the thread gets locked.
     
    Last edited: Jan 28, 2020
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  18. LookAtYou

    LookAtYou Member

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    Why would it get locked?
     
  19. JERRY

    JERRY Member

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    ballistic gel is suppose to simulate soft tissue in a human body, nothing more. it is used to check bullet design performance through a consistent median. the 12 to 18 inches of preferred penetration is a guestimate needed to reach vital organs if first encountering intermediate barriers like muscle, an arm bone, muscle, muscle then ribs, standard wooden house door et cetera. pick anywhere on your body where there is a vital organ and tell me how deep it is from the surface. average depth to get most any human vital organ is 4".
     
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  20. LookAtYou

    LookAtYou Member

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    Yea, and I want to be prepared for any sized attacker, so I tend to lean towards the 15"+ penetration JHP's, which in 9mm is pretty rare. Good thing the 135 Grain Federal Hydra Shok Deep exists.
     
  21. Shawn Dodson

    Shawn Dodson Member

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    Good loads exist that penetrate 13-15" in bare gel and 14-16" in 4LD gel. I use Federal HST 9mm 147gr in my G19, G26, G43 and Ruger PC9. It's an excellent load for 9mm.
     
  22. LookAtYou

    LookAtYou Member

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    Yea, I saw that exact load (147 Gr HST) do 14.8" in Professional 4LD Gel test. HSD has less recoil and more penetration it seems, at the cost of some expansion.
     
    Last edited: Jan 28, 2020
  23. LookAtYou

    LookAtYou Member

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    I've heard the argument that you can poke your finger into gel if you push hard enough, but not into skin. What would be the explanation of this, if skin truly doesn't provide resistance to a bullet on entrance? Kinda the same as how a calibration BB goes 4" into gel, but can barely break skin. What gives?
     
  24. 94045

    94045 Member

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    Years ago DocGKR sent me a Federal LE9T5 test that did 14.5" in Bare Gelatin and 16.1" in FBI Heavy Clothing with a 4.25"(?) if I recall correctly. It's available cheap right now as Fed is discontinuing it.
     
  25. LookAtYou

    LookAtYou Member

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    Checked it out, I don't prefer +P ammo. Want to have as least recoil as possible.
     
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