A gel expert explains

[Pudge]

Why not, could it?

 

[Walt Sherrill]

No, I'm questioning why the officer ended up disoriented and on his back.

I read your responses and I didn't really see you asking a question about WHY the officer ended up disoriented and on his back. I only saw you suggest that his disorientation and fall was due to energy transfer -- as nothing else made sense to you.

In fact, there are many possible ways to explain the officer's disorientation and why he ended up on his back, but I don't think any of them have anything to do with energy transfer.

The POWER of energy transfer seems to be an article of faith for you -- but it will have to remain an matter of faith, as you can offer no explanation for its assumed effect.

You could, with as much evidence as you've offered for "energy transfer" (i.e., none) also say the infamous the invisible red kangaroo knocked him down. (To do that, however, you must have faith that the invisible red kangaroo exists and is also capable of knocking down someone in a gun fight without leaving a trace of its presence. Why an invisible red kangaroo might WANT to do that must also remain a mystery.)

 

[RetiredUSNChief]

Did you watch the video? He didn't know he was in a gunfight until he was on his back. It wasn't a psychological reaction. In any case what put him on his back and disoriented him was not the destruction of tissue caused by the projectile. I believe it is fairly obvious that the officer was concussed. I also believe that the severity of the concussion would be affected by the power of the round and the energy it delivered. I also believe that Dudedog's temporary loss of control of his leg was not due to physical destruction of tissue or psychological trauma, but a disruption of function due to the energy delivered to his body, and varying the amount of energy would change the level of disruption. I think that equating the disabling effect of the energy delivered to the officer's head with the recoil experienced by the shooter is unrealistic, and that the energy of a round can have a profound effect on a gunfight in addition to how deep it drives a projectile. Just because that effect is not easily quantifiable or demonstrated in a gel test does not mean that it does not exist.

Not "PSYCHOLOGICAL"...."PHYSIOLOGICAL".

A physical reaction of the body caused by a neuro-muscular reaction brought on by the stimulus of being shot.

The BODY was REACTING to the physical shock of being shot, in other words.

To give a simple example, if I lift your leg using my hand, I'm using energy to generate force which will cause your leg to lift. However, if I tap that whateverit'scalledspot right under your kneecap, a physiological response will be induced which will make your own leg kick out.

 

[RetiredUSNChief]

You cannot say that unequivocally. You have already said that you do not know the reason, and speculated that it cannot be known.

Did you watch the video of the officer's account? There are some who have responded to my questions about that video, who's responses make me suspicious that they are willing to judge conclusions drawn from the testimony without listening to the officer's account. Did you watch it?

Yes. Yes, we CAN say what we're saying unequivocally because we can DEMONSTRATE the physics behind it.

We can indeed say with certainty that this person was NOT knocked down on his back with respect to the kinetic energy of the bullet he was struck with in any way, shape, or form like Hollywood might depict for visual drama in the movies.

The physics of this is real and entirely subject to verification by experimentation.

 

[RetiredUSNChief]

You're saying that being shot point blank in the face with a 230 grain .45acp cannot cause a concussion?

OK, WHERE did we get off on this tangent?

Not only have you completely changed the subject, you've also completely changed the circumstances, especially with respect to physics and trauma.

A human head weighs about 10 pounds. Just from a purely scientific standpoint vis-a-vis physics, the reaction of a 10 pound object being hit with a 230 grain projectile will be different than the reaction of a 180 pound object being hit by a 230 grain projectile.

But more to the point here, even THIS example can be mitigated by the fact that the military has long invested in helmets designed to protect the human head from not only penetration, but trauma.

And even MORE to the point here, the danger to the brain isn't just by the physical shock of the whole head being moved suddenly as a complete and undamaged unit (which is what damage solely by energy transfer as being discussed is about), it's the physical damage caused by structural damage to the skull and the resulting formation and propagation of the resulting shockwaves through the brain matter.

So yeah...you CAN cause a concussion this way, and very easily. However, what you're NOT going to do is throw that head with the attached 170 pound person on the ground through kinetic energy transfer. Which is what we've been discussing here.

 

[C-grunt]

In my last gunfight last year I shot a guy twice in the chest with .223 55 grain hollowpoints. Both produced approximately 1100 lbft of energy and both expanded and fragmented inside the guy and didn't exit..... ie "dumped all of it's energy".

The first shot, the guy flinched as if the sound startled him. He then charged me. The second shot, he showed no sign he had been shot at all. Truthfully at the beginning I believed I had missed both shots because of his lack of reaction.

 

[Zendude]

The best explanation regarding gel testing is that gel is just a target media to compare the characteristics of different cartridges. The gel itself is somewhat irrelevant.
If a cartridge has proven effective through actual use, then its “gel numbers” are used to determine what other cartridges might be just as effective, more effective, or less effective.

 

[Kleanbore]

The best explanation regarding gel testing is that gel is just a target media to compare the characteristics of different cartridges. The gel itself is somewhat irrelevant.

That was not the position of those who developed it, nor was that their objective.

 

[Double Naught Spy]

I thought this was a great quote and quite relevant to this thread...

"Gelatin testing and the results from it are only tools to be used. If you consider either anything more than an indication of terminal performance or lethality potential, you might be a Jell-O junkie—Don’t be a Jell-O junkie."
https://www.shootingillustrated.com...gel-testing-what-it-does-and-doesnt-tell-you/

 

[Walt Sherrill]

thought this was a great quote and quite relevant to this thread...

"Gelatin testing and the results from it are only tools to be used. If you consider either anything more than an indication of terminal performance or lethality potential, you might be a Jell-O junkie—Don’t be a Jell-O junkie."

If you mean using Ballistic Gelatin as a testing medium doesn't really tell us much about how a particular round will perform in human/animal tissue, I agree. (And that's what I thought you were saying.) If you mean something else, then you'll have to explain.

Gelatin isn't resilient and does not stretch (and sometimes return to it's original position) like tissue; it also doesn't have hard bones like human or animal bodies. It was designed to be a proxy for porcine tissue, which is similar to human tissue -- muscle, ligaments, etc. Not bone or internal organs. How a round disrupts gelatin is nothing like how that same round will disrupt tissue -- especially tissue of a living animal/human.
.

 

[RetiredUSNChief]

My understanding of ballistics gelatin is that it's a standardized, homogenized medium by which basic projectile penetration and expansion performance may be measured against and compared to.

I also understand that it's supposed to approximate that of soft tissue in humans.

This eliminates all the other variables which cannot be otherwise accurately quantified and replicated on an experimental basis. Things like bone, cartilage, variations in density/thickness of the various types of tissues, varying effects of damage to different organs, etc.

Ballistics data gathered from this medium can thus be compared across the board ONLY because it's the same, standardized medium.

THUS...one can compare the relative penetration abilities between even different calibers, bullet masses, and bullet designs WITHIN THE SAME MEDIUM, and use that data to draw reasonable conclusions with respect to their performance in soft tissue (human or otherwise).

For example, bullet X, which reliably penetrates 4 to 6 inches deeper in ballistics gel than bullet Y, can be reasonably said to be more likely to penetrate deeper in soft human tissue than bullet Y as well. Not that it WILL penetrate 4 to 6 inches deeper in human tissue, nor do this all the time, or achieve this amount of penetration when hitting bone along the way.

 

[Shawn Dodson]

If you mean using Ballistic Gelatin as a testing medium doesn't really tell us much about how a particular round will perform in human/animal tissue, I agree. (And that's what I thought you were saying.) If you mean something else, then you'll have to explain.

Properly prepared and calibrated type 250A ordnance gelatin does indeed tell us how a bullet will perform in soft tissues.

Gelatin isn't resilient and does not stretch (and sometimes return to it's original position) like tissue; it also doesn't have hard bones like human or animal bodies. It was designed to be a proxy for porcine tissue, which is similar to human tissue -- muscle, ligaments, etc. Not bone or internal organs. How a round disrupts gelatin is nothing like how that same round will disrupt tissue -- especially tissue of a living animal/human.
.

Gelatin isn't resilient? So it's like a block of modeling clay, eh?

What bones "should" be in gelatin to make it "realistic"? Tell us how the inclusion of bones matters?

Fackler and MacPherson proved the opposite findings in every statement in your paragraph.

 

[Double Naught Spy]

Tell us how the inclusion of bones matters?

Strange as it may seem, bullets can, and often do, behave very differently when they hit bone. Those beautiful petal blooms are often not so beautiful anymore, torn off, flattened in the wrong direction, etc. Their paths may actually be altered.

 

[Shawn Dodson]

Well no duh!

The only terminal performance we desire when bone is encountered is for the bullet to blast through to reach and destroy soft tissues that are critical to immediate survival. That's it!

Bone? The FBI windshield glass test has shown to also reasonably represent terminal performance when a bullet hits bone.

 

[Double Naught Spy]

YOU asked the DUH question. YOU get the DUH answer.

 

[pblanc]

Ballistic gelatin simulates only the density of human muscle tissue. There are many other properties of muscle tissue that are pertinent to terminal ballistics that are not simulated.

 

[Walt Sherrill]

Bone? The FBI windshield glass test has shown to also reasonably represent terminal performance when a bullet hits bone.

I found a review (performed by the California Highway Patrol (CHP) of the FBI windshield glass tests, but not the FBI tests itself. I could find nothing in that review that said anything about how JHP penetration through auto glass compared to JHP penetration through bone. Perhaps you have access to have another source that addresses the "bone" part of your statement, above? I've not found much addressing BONE penetration.

The CHP review (based on and citing FBI study charts) and found in an article called Windshield Glass Penetration, in WOUND BALLISTICS REVIEW from the JOURNAL OF THE INTERNATIONAL WOUND BALLISTICS ASSOCIATION Vol 2, Nr. 4. The CHP study addressed only .40 S&W and .45 ACP rounds -- possibly because that was what the CHP used in duty weapons. The FBI study may have used other calibers as well, including 9mm, but the studies cited here are about 30 years old and 9mm performance has apparently improved considerably since the study was done.

I was surprised to find that the FBI study showed that .45 JHP (using Ranger or similar JHP ammo) had virtually no deflection at most angles, while .40 S&W had varying amounts of deflection at almost any angle. The CHP review, however, didn't address 9mm. Part of the .45 rounds performance seemed to be due to the fact that the larger caliber .45 round had a different effect on the glass, shattering it into smaller particles that had less effect on bullet travel.​

Another review, seen in the American Rifleman -- apparently the same study used by the CHP review, above -- addresses windshield glass penetration, and can be found here: https://www.americanrifleman.org/articles/2015/4/16/throwback-thursday-the-fbi-ammo-tests/

The American Rifleman article has an interesting comment from Dr. Fackler, addressing secondary wound damage (the disruption of tissue caused by bullet travel).

“These studies,” Fackler said, “ranked bullets solely according to the temporary cavity produced in ordnance gelatin. They assumed that incapacitation of the human target by a given bullet is directly proportional to temporary cavity size. No physiologic mechanism was even postulated for this supposed effect—much less proved. Temporary cavity size for a given bullet can be increased very simply by decreasing bullet weight and increasing velocity." But human tissues are quite elastic and suffer little or no permanent damage or bleeding from the temporary cavity formed by a bullet, Dr. Fackler holds. The only way a bullet can produce a significant effect is to directly penetrate the tissue.

Dr. Fackler concluded: “The critical consideration is that the bullet produce its permanent tissue disruption to sufficient depths to insure major vessel disruption from any angle.”​

My interpretation of his comment is that the massive disruption of ballistic gel seen in various Ballistic Gel studies will almost never have a similar effect in animal/human tissue.

If anyone has a direct link to the FBI study, please share it with us.

 

[pblanc]

Ballistic gelatin does not have the tensile strength, nor the elasticity of muscle tissue. It is homogenous in density whereas muscle tissue bundles are invariably invested by fascial tissue of significantly greater density that a projectile must pass through. And ballistic gelatin is isotropic. It doesn't care what direction it gets shot at. Human tissue, including muscle, is anisotropic. Density and tensile strength are significantly dependent on the angle at which a projectile strikes the tissue.

The "studies" that Dr. Martin Fackler was referring to were those that led to the "Relative Incapacitation Index" (RII), a completely idiotic exercise in mental masturbation that purported to quantify the potential of various handgun cartridges to incapacitate based on their performance in ballistic gelatin, which included high speed video of the temporary cavity produced in the gelatin, with some calculus thrown in to compute a "theoretical cavity" that was then used to compute the relative incapacitation index.

Anyone who really wants to waste their time this Black Friday can read all about it here:

https://www.ncjrs.gov/pdffiles1/Digitization/87004NCJRS.pdf

 

[Shawn Dodson]

Ballistic gelatin simulates only the density of human muscle tissue. There are many other properties of muscle tissue that are pertinent to terminal ballistics that are not simulated.

Penetration of a 9mm bullet at 1000 ft/sec is resisted by an inertial force of about 800 pounds; it is obvious that the presence or absence of a 3 to 5 pound shear force makes no practical difference in the penetration at this velocity. This also explains why the fact that gelatin fractures more easily than tissue does is not important.

The extension of these dynamics to soft tissue variation is obvious. Different types of tissue present different resistance to finger probing by a surgeon, but the surgeon is not probing at 1000 ft/sec. Different tissue types do have differences in the amount of shear force they will support, but all of these forces are so small relative to inertial forces that there is no practical difference. The tissue types are closer to one another than they are to water, and bullet expansion in water and tissue are nearly identical at velocities over 600 ft/sec where all bullet expansion takes place (See Bullet Penetration for a detailed explanation of bullet expansion dynamics).

Since inertial forces depend on accelerating mass, it makes sense that these forces should be lower at lower velocities (because the penetrated material cannot be accelerated to a velocity higher than the bullet). Shear forces have little velocity dependence, and as a result, shear forces are a much larger fraction of the total when bullet velocity is below the cavitation threshold. This low velocity effect is the reason that total bullet penetration depth is much different in water and in tissue or a valid tissue simulant.

As a result of the penetration dynamics, most soft solids with a density very near soft tissues (i.e., near the density of water) are satisfactory tissue simulants when shear forces are not important. However, total penetration depth depends significantly on dynamics at velocities below 400 ft/sec, so most materials do not properly simulate penetration depth. The total bullet penetration depth in tissue and a valid tissue simulant should be the same; standard practice is to use calibrated gelatin to insure this. In effect, gelatin calibration is done to ensure that the shear forces in the gelatin are the same as in typical soft tissue (as described in Bullet Penetration, the technical parameter used in the dynamic is viscosity).

-- “Wound Ballistics Misconceptions.” (Duncan MacPherson, Wound Ballistics Review, 2(3): 1996; 42-43)

Distilled:
When a bullet is expanding, the inertial forces (velocity + density) are so very much larger than the shear forces that the shear forces can be ignored.

 

[Kleanbore]

Good indfo, Shawn.

 

[Shawn Dodson]

My interpretation of his comment is that the massive disruption of ballistic gel seen in various Ballistic Gel studies will almost never have a similar effect in animal/human tissue.

For a better understanding of disruption observed in ordnance gelatin and how it compares to disruption in human soft tissues I refer you to:

1. Fackler ML. Bellamy RF. Malinowski JA. "The wound profile: illustration of the missile-tissue interaction." Journal of Trauma-Injury Infection & Critical Care. 28(1 Suppl):S21-9, 1988 Jan.
2. Fackler ML. Malinowski JA. The wound profile: a visual method for quantifying gunshot wound components. Journal of Trauma-Injury Infection & Critical Care. 25(6):522-9, 1985 Jun.

 

[pblanc]

I have personally seen 38 Special and 9 mm projectiles deviated completely off course when they struck the fascia of the anterior abdominal wall of the investing fascia of the lateral thigh musculature. Try simulating that with ballistic gelatin.

 

[Shawn Dodson]

Ballistic gelatin does not have the tensile strength, nor the elasticity of muscle tissue. It is homogenous in density whereas muscle tissue bundles are invariably invested by fascial tissue of significantly greater density that a projectile must pass through. And ballistic gelatin is isotropic. It doesn't care what direction it gets shot at. Human tissue, including muscle, is anisotropic. Density and tensile strength are significantly dependent on the angle at which a projectile strikes the tissue.

Modeling terminal ballistic performance in fluids/liquids requires more than matching density (ρ) to achieve dynamic equivalence with soft tissue. In order to properly represent terminal performance in soft tissue, the candidate fluid/liquid must also possess the same bulk modulus (K) and internal sonic velocity (c) which are all related to one another in the Newton-LaPlace formula— c = √(K/ρ)

Compared to the respective values of c, ρ, and K in water, 10% ordnance gelatin, and human soft tissue—

H2O: c = 1,497 ms-1, ρ = 999.87 kg/m³, K = 2.24 GPa
10% ordnance gelatin: c = 1,494 ms-1, ρ = 1,040.00 kg/m³, K = 2.32 GPa
Typical values for human soft tissue: c = 1,540 ms-1, ρ = 1,020 kg/m³, K = 2.42 GPa

 

[Shawn Dodson]

I have personally seen 38 Special and 9 mm projectiles deviated completely off course when they struck the fascia of the anterior abdominal wall of the investing fascia of the lateral thigh musculature. Try simulating that with ballistic gelatin.

These results can be replicated in ordnance gelatin. Fackler showed that when the exact circumstances are replicated the results in ordnance gelatin are virtually the same.

 

[pblanc]

These results can be replicated in ordnance gelatin. Fackler showed that when the exact circumstances are replicated the results in ordnance gelatin are virtually the same.

No they are not. Projectiles do not get deflected completely off course in homogenous ballistic gelatin.