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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. lysanderxiii

    lysanderxiii Member

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    10% Ballistic Gelatin is like the NHS crash rating, only less so.

    If Car A has a 5-star rating it is probably safer than Car B with a 3-star rating, but by how much? Who knows. What are your chances of being injured? Who knows.


    It gives you an idea of which bullet expand more for a given velocity, but it does not predict terminal effects.

    If Bullet A expands more than Bullet B in gelatin, it probably will expand better in tissue. But how that equates to "stopping power"? who knows.
     
  2. bdickens

    bdickens Member

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    "Stopping power" is fantasy.
     
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  3. ATLDave

    ATLDave Member

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    Stopping power is a fantasy if someone thinks that they're talking about the ability to physically push a human over via conservation of momentum. Everyone here knows that cattle rustlers don't go flying backwards through plate glass windows in the saloon just because that's what the movies show.

    Stopping power is not a fantasy if it means the propensity of a projectile to produce the desired behavior in a target - i.e., cessation of aggression. Certainly a higher percentage of people who are shot in the torso with, say, an expanding .308 projectile at 2700 fps will stop running at you with a knife than similar people shot with a .22lr. Neither is a 100% proposition, nor is either a 0% proposition, but one of those rounds has more propensity to stop - more stopping power.
     
  4. Hartkopf

    Hartkopf Member

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    I did some testing with a modified gel block and posted the results here:

    https://thehighroad.org/index.php?t...ck-test-9mm-40s-w-45acp.860472/#post-11329184

    Also is an example of how threads get locked
     
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  5. Shawn Dodson

    Shawn Dodson Member

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    You're not poking your finger at 1000 fps.

    Skin possesses greater shear force resistance than gelatin.

    Where'd you hear that a BB barely breaks the skin at 600 fps?

    If you're interested in learning about soft tissue simulants then I encourage you to get this book - https://www.amazon.com/Bullet-Penetration-Modeling-Incapacitation-Resulting-ebook/dp/B00L7CSV7E
     
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  6. LookAtYou

    LookAtYou Member

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    Ah, just did a quick search, and found that at 331 fps, a 0.177 Cal BB perforates skin, and also at that velocity can fracture certain bones (fracturing starting at 200-250). So since skin has greater shear force than gel, than it does have some sort of, albeit very minor, resistance to a bullet. I think entry of skin being equal to 2"ish of gel may not be too far off?
     
  7. LookAtYou

    LookAtYou Member

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    Interesting. It seems that "KleanBore" initially came into the thread on, what's a less colorful way to say this... "Bad Timing". Would you be willing to test 135 Gr Federal Hydra Shok Deep in the same testing format you did the others, if you ever get your hands on the ammo?
     
  8. Hartkopf

    Hartkopf Member

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    I mostly wanted to test large expanding unbonded vs smaller expanding bonded ammo in something “tougher” than plain clear gel. I’m not really interested in pursuing this much further. It was just something I slapped together for a one time test.
     
  9. LookAtYou

    LookAtYou Member

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    Ok.
     
  10. Shawn Dodson

    Shawn Dodson Member

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    Skin resistance to bullet penetration has been tested and it has no effect on overall penetration depth except when a bullet attempts to exit through unshored skin.
     
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  11. LookAtYou

    LookAtYou Member

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    So I guess my question becomes, even though that gel is easier penetrate than skin (the finger in gel scenario), then what is Shear Resistance? Or what makes skin nothing to a bullet then? Is it the velocity of the bullet? What makes a finger not be able to push through gel, but not skin, even though gel is made to represent tissue?
     
  12. MTMilitiaman

    MTMilitiaman Member

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    I too have read somewhere that penetrating skin, especially exiting skin, can be the equivalent of several inches of penetration in gel. This is interesting, but I think it misses the point.

    Gel is not used to give us a correlation to predict real world penetration in living tissue, but rather because accurately predicting real world penetration in tissue is so unrealistically complex as be impractical. Gel is used because it provides a homogeneous, calibrated medium that allows for repeatable, scientifically valid results. Scientific method requires there to be only one control in an experiment. The control is the thing that changes. Using meat targets or other complicated mediums means that any difference in our results can be due to either a difference in our testing medium or the ammunition, thereby making the results unrepeatable and scientifically invalid. Using a simple homogeneous substance like ballistics gel gives us something we can calibrate and means that any difference in our results can only be due to the control, the ammunition being tested, thereby making the results repeatable and valid. The 12 to 18 inch standard is derived to give us a relative comparison. We know from actual shootings that bullets capable of penetrating at least 12 inches of gel will likely penetrate far enough in actual tissue to reach vital structures from most angles, and those penetrating less than 18 inches will likely provide a responsible level of penetration not likely to "over penetrate" an assailant with enough remaining velocity and momentum to be dangerous to innocent bystanders. But living bodies are too complicated for us to have an equation whereby we can accurately predict how far a given projectile will penetrate in living tissue given "x" amount of penetration in gel. We have guidelines, not rules.

    One such guideline is that bullets producing at least 25 gr x fps of momentum are less likely to be deflected by bones or changes in density. We know that bullets need an impact velocity of about 2000 fps or more to show a temporary stretch cavity, and so generally speaking handguns are not going to use energy very efficiently, and are only going to show damage done by the permanent crush cavity created by tissue physically displaced by the actual projectile. Exceptions may exist to all of these guidelines, so we consider them more generalizations than set in stone rules, but generally speaking, momentum is more important in handguns than energy. Energy favors velocity because velocity is squared in the calculation. So lighter faster bullets will usually have more energy and expansion, but less penetration. Heavier for caliber bullets have higher sectional densities and more momentum, and typically exhibit less expansion and more penetration. If you are worried about deflection or lack of penetration, it is generally better to give up some energy and go with a heavier for caliber, slower projectile.
     
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  13. LookAtYou

    LookAtYou Member

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    Very good post, thank you. I guess my only gripe are the first 2 sentences.

    Gel is not used to give us a correlation to predict real world penetration in living tissue, but rather because accurately predicting real world penetration in tissue is so unrealistically complex as be impractical. Gel is used because it provides a homogeneous, calibrated medium that allows for repeatable, scientifically valid results.[/QUOTE]


    While I understand that gel testing is useful for comparing different ammo in the same medium, it isn't completely relevant to the main thing people want to know. "How far will the bullet penetrate in humans? How far will it penetrate in a body." It's like ballistic gel tests only reach a certain point of relevancy, all but missing the MAIN critical point. Basically, for example, after TONS of ballistic testing, a consensus has been reached that Bullet "X" is best, it penetrates 18" with 2" Expansion. Cool. Now, most importantly, HOW DOES THAT TRANSLATE TO A BODY? If that connection can't be made, it's like leaving the final, and most relevant piece that matters the most, the piece that people have consulted gel testing for in the first place, is missing. Kinda see what I mean?
     
  14. lysanderxiii

    lysanderxiii Member

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    Too many variables to answer that question with any sort of precision.

    Most people consult gelatin tests with unrealistic expectations of what can be learned.
     
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  15. Hartkopf

    Hartkopf Member

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    All you can do is take ammo with known penetration and expansion in gel, then go shoot some pigs and compare. I suggest standing the pigs up like a human.
     
  16. ClickClickD'oh

    ClickClickD'oh Member

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    This is the same argument that QED kept making that got the other thread shut down.

    The answer is that what you want to know is unknowable unless you want to go out and shoot a lot of living bodies. Even then, the data you would get from doing so won't be very useful in a meaningful way since almost every shot into a living body will show different results. Even if you try to shoot every living body in the same place, you likely won't hit exactly the same structures. Some shots may hit bones, some may hit tendons, some may hit organs, some may just get flesh. So, you won't be able to ever say with any level of confidence, "this is exactly what this bullet does when it hits a body". Oh, and there might be a bit of public outrage with all the bodies getting shot.... and I don't even want to know how you got them all naked, or else your results are going to be even more skewed due to variances in clothing.

    Knowing exactly what any particular bullet will do in a real body is unknowable.

    That's why you test in gel. Gel is consistent and repeatable. Good performance in gel is generally a good indication of good performance in a body. So, for your example, 18" of penetration with 2" expansion (mother of god!) would most likely do really well in a body since it is on the higher end of the penetration scale and exhibits amazing expansion. One of the important things to remember about the gel test is that 12"-18" of penetration in gel doesn't mean the bullet is expected to go 12"-18" in a body. It means that the bullet can be expected to penetrate deep enough into a human body to hit vital organs despite the presence of expected target obstructions, be they thick clothes, bones, an arm, etc etc, and not be an extremely dangerous projectile if/when it comes out the other side. A bullet that travels less that 12" in gel mean that it isn't going to reliably penetrate to vital organs if it has to pass through thick clothes, bones, an arm etc. It still might do just dandy without those things though. A bullet that travels more than 18" inches in gel means that it's likely to exit a target retaining dangerous energy and velocity, especially so if it doesn't strike any of the expected intermediate barriers.

    So, TLDR. No, gel doesn't tell you exactly how a bullet will perform in a body, but it does give you a decent idea of how it will perform, if you know the criteria being tested and understand that the gel represents a composition of criteria regarding the target.
     
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  17. MTMilitiaman

    MTMilitiaman Member

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    How far does it penetrate in which body? From which angle and distance? That is why it is unrealistic to try and equate a certain level of penetration in gel with a certain level of penetration in tissue. Living tissue is complex. It varies in density. No two bodies are the same. That is also why testing on pigs or other "meat targets" is interesting, but not scientifically valid, and why the field of terminal ballistics is not an exact science. Accurately predicting performance of a projectile in a uniquely complex target under dynamic circumstances is beyond our current level of technology and understanding. So again, we have guidelines, not rules. We can say "generally +/- 20% of penetration in gel," for example, but even this broad generalization will have plenty of exceptions to disprove it as a rule. Every body is different. There are too many factors to consider to simply plug a couple numbers into an equation and derive an accurate estimate of penetration. If that is what you are seeking, you will not find it with gel testing, or any other available technology. The only way to figure out how a particular bullet will behave in a particular body from a particular shot presentation and distance is to actually take the shot and find out.
     
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  18. LookAtYou

    LookAtYou Member

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    Again, thank you. This is also why, with knowing that adequate penetration is the most important factor in handgun bullet effectiveness, that I simply cannot be comfortable with a bullet that does the bare minimum (12") penetration in gel tests. For me, 15"+ penetration is a must, yet most JHP's, until you hit .357 caliber, fall into the low end (12-14.5") of the 12-18" range. With knowing how it's more common than ever for people to be of a bigger stature, I ain risking nothing lol.
     
  19. Hartkopf

    Hartkopf Member

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    Another reason I did my modified gel block testing was to compare different ammo against simulated layers of "connective tissue." I sorta had the same questions in mind that you have but I didn't want to shoot, dissect and clean up pigs.

    I was told by an ex cop who also worked in the morgue to use 9mm and specifically Gold Dots because it reliably penetrated deep enough in real world shootings. He said next best is Hornady and Fed HST. Larger calibers did not penetrate as well. I know there is other effective ammo but GD was his favorite because of results he's seen.

    Look at the results of my test and you will see GD 9mm penetrated the deepest and the 147gr HST did very well. The 45ACP 230gr HST is a great round but was stopped at the last layer at 10". I believe (all my opinion) that a large, charging bad guy who gets his arm up as a sacrificial shield, could keep a .900" HST from penetrating through to his heart. But a 124gr +p Gold Dot would likely do the job. That's just my opinion of one hypothetical situation but my reasoning for needing plenty of penetration.
     
    Last edited: Jan 30, 2020
  20. Odd Job

    Odd Job Moderator Staff Member

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    We've had a thread on this already.
    Closed as duplicate.
     
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