[Michael Courtney]

.40 Caliber Pressure Wave Effects

We had an opportunity this weekend to perform an informal field necropsy on a 180 lb 7 pt buck shot with a 135 Grain .40 caliber Nosler JHP at approximately 1350 FPS impact velocity. Though fired from a muzzleloader, this impact velocity closely approximates the impact velocity of the same bullet fired from a .40 S&W. This load produces one of the larger pressure waves available from JHP ammo in 9mm, .40S&W, .45 ACP, or .357 Sig. This buck was shot during a special youth-only hunt, and the young hunter was gracious enough to allow a couple of scientists access to his deer.

The effects of the pressure wave on tissue were impressive. The bullet entered just in front of the third rib (counting from the back) on the left side, pulverized a large (1.5” diameter) on the inside of the rib cage and in the liver, entered the left lung producing a large (1” diameter) pulverized region, entered the right lung producing a pulverized region that gradually shrank in size to the recovered diameter of the bullet (0.58”), exited the rib cage just in front of the 11th rib (counting from the back) and was recovered in the muscles of the right shoulder. The direction of the wound agrees with the account of the shot that the buck was mostly broadside, but angled slightly away with his head down grazing.

According to the PCC-only view of handgun bullet wounding (espoused by Fackler/IWBA adherents), the expected wound channel (which assumes crushing is the only mechanism) should be roughly cylindrical in shape, and have a diameter roughly equal to the recovered diameter of the bullet. The volume of this expected wound channel is widely known as the permanent crush cavity (PCC) and given by the frontal area of the recovered bullet times the penetration depth (12”). This gives an expected wound volume of 3.17 cubic inches.

What we actually observed is a truncated cone region of pulverized tissue with a diameter of 1.5” on the entrance side, and gradually narrowing to 0.58” on the exit side of the rib cage. The actual volume of this truncated cone of pulverized tissue is 12.18 cubic inches, or nearly 4 times the volume predicted by the PCC-only view of wounding via handgun bullets.

In addition, we observed a region of severe to moderate hemorrhaging along the wound channel that was 5” in diameter at entrance, narrowed to roughly 3” in diameter at the medial surface of the left lung and gradually shrank in size to merge with the bullet diameter where the bullet exited the rib cage. This region of hemorrhaging has an approximately truncated cone shape with a volume of 119.3 cubic inches.

We believe that the pressure wave is responsible for this hemorrhaging, though we cannot rule out the temporary stretch cavity for some regions. However, the 5” diameter of hemorrhaging of the muscular tissue surrounding the entrance wound is much larger than the expected TSC at this point. This is the effect that hunters associate with high-velocity rifle bullet wounds and refer to as bloodshot meat. Since the pressure wave is more strongly directed backward than the TSC, it makes sense that this hemorrhaging is due to the pressure wave.

We also observed mild hemorrhaging along the abdominal walls and rear rib cage on the right side. This is the area directly opposite from the entrance wound, but considerably rearward from the point where the bullet exited the rib cage. Thus this region was out of reach of both the permanent crush cavity and the temporary stretch cavity, and it seems that the most likely cause of the hemorrhaging was the pressure wave.

Inspecting the site of the shooting revealed that the deer ran 54 yards (straight line distance) from where it was shot to the point where the carcass was recovered. This is in good agreement with our empirical models which predict the average drop distance from the IWBA-type PCC volume and the peak pressure wave magnitude. In spite of the absence of an exit wound, there was an extremely profuse blood trail spread along the path the deer ran.

The wounds we observed for the 135 grain Nosler JHP are very similar to those observed in earlier studies with the 115 grain Triton Quik-Shok at .357 Sig velocities. In both cases, there is substantial tissue damage and destruction beyond the tissue crushed directly by the projectile. These two loads generate comparable pressure waves.

The tissue damage we observed from the 135 grain Nosler JHP is markedly different from that which we have observed on earlier occasions with lower pressure wave bullets such as the 147 grain Winchester 9mm bullet at 9mm velocity levels. The tissue damage due to the 147 grain 9mm bullet is very much in accordance with the PCC-only view espoused by Fackler/IWBA adherents: a nearly cylindrical region of crushed tissue with a diameter well approximated by the expanded diameter of the bullet. There is little tissue damage beyond the tissue crushed directly by the bullet.

This same 135 grain Nosler JHP bullet is also available in 10mm. We estimate the pressure wave in the 10mm Double Tap loading to be 50% larger than the pressure wave generated at 40 S&W velocities. Interesting. The performance potential of this bullet is almost enough to make me trade in my .357 Sig.

Michael Courtney

[mete]

Thanks Michael, keep doing the studies , we'll learn a few things !

[Shear_stress]

Very interesting. With all the speculation about wounding mechanisms flying around, it's great to have some empirical evidence.

It's not too surprising that a pressure wave would cause hemorraging in a region surrounding the wound. Tissue is a relatively dense, roughly incompressible medium that will amply transmit pressure pulses that may be more than enough to burst capillaries in a fairly wide radius around the wound. Add to that the body's propensity for inflammatory response (especially at an elevated heart rate), and you've got a big mess in there.

Before anyone runs out and tries to compare this to a wound caused by a high-powered rifle, remember that there is a lot more velocity at work there. In fact, the sudden rise and drop in pressure in the wound track of a rifle bullet may be enough to cause cavitation in the tissue (in addition to tissue stretching and a big honkin' pressure wave). Yuck.

Keep up the good work!

[P95Carry]

Most detailed and useful report Michael - thank you :)

[LightningJoe]

Thanks for a little light. It's dark in here.

[JohnKSa]

The jello junkies are going to string you up--sho' nuff...

[ghost squire]

http://www.firearmstactical.com/images/Wound%20Profiles/45%20ACP%20WW%20STHP.jpg

http://www.firearmstactical.com/images/Wound%20Profiles/45ACP%20230gr%20FMJ.jpg

Doesn't look cylindrical to me! From a Facklerite/IWBA site.

I have a question, did the bullet go through the heart?

Also keep in mind that flesh that is hemmoraghed by a bullets energy outside of the crush cavity takes several seconds to even start bleeding.

I'm not trying to detract from your work, just put it in perspective. If the bullet pulverized the heart without actually touching it, then I am very suprised and will have to rethink my stance on the entire matter of wound ballistics.

[Michael Courtney]

http://www.firearmstactical.com/images/Wound%20Profiles/45%20ACP%20WW%20STHP.jpg

http://www.firearmstactical.com/images/Wound%20Profiles/45ACP%20230gr%20FMJ.jpg

Doesn't look cylindrical to me! From a Facklerite/IWBA site.


The diagrams you reference do indeed show the permanent crush cavity to be cylindrical. The non-cylindrical outer regions represent the temporary stretch cavity (TSC). Fackler and the IWBA folks have asserted adamantly on many occasions that the TSC does not cause significant wounding in handgun bullets.

We believe that the pressure wave is more important than the TSC in incapacitation via handgun bullets, but since there is a large correlation between the two, it is hard to be absolutely certain at this time. However, from our observations, we do have a high level of certainty that there is some effect other than the PCC that is responsible for a great deal of tissue damage. Our observations also indicate that at least some of this damage is more likely due to the pressure wave than the TSC, because we observe some wounding in tissue beyond the reach of the TSC.

In any event, the observation of a handgun bullet at 1350 FPS creating a truncated cone of pulverized tissue with a volume nearly 4 times the PCC volume is contrary to what one would have expected from the IWBA opinion that the permanent crush cavity is the most important and only reliable predictor of handgun bullet effectiveness. In contrast, it is quite consistent with emperical models based on the Strasbourg Goat Tests and/or Marshall and Sanow OSS data which suggest that a model including both the PCC and the pressure wave magnitude (or TSC) can predict relative handgun bullet effectiveness.

[url]
I have a question, did the bullet go through the heart?


No.


Michael Courtney

[ghost squire]

Fackler and the IWBA folks have asserted adamantly on many occasions that the TSC does not cause significant wounding in handgun bullets.

And they appear to be correct in the context that they say that in.

I very seriously doubt that destruction of random tissue is going to aid significantly in stopping an attacker in a self defense situation. Now, the bullet did go through both lungs, but if I am not mistaken, any significant hole in a lung is going to deflate it and make it stop working. I might be wrong here... Therefore the "pressure wave" and TSC didn't appear to help all that much here.

Now if that particular cartridge has the ability to destroy the heart purely by TSC or "pressure wave", then I am very impressed, and the IWBA would certainly have to take notice.

But according to my research a minimum velocity of 1500 FPS is required to do that.

Could you please define what the difference between a pressure wave and the TSC is? I haven't heard that term before in terminal ballistics speak.

[Shawn Dodson]

The diagrams you reference do indeed show the permanent crush cavity to be cylindrical. Yes indeed, they are incorrect. Permanent cavity diameter is larger at the beginning of the wound track and decreases in diameter as velocity decreases.

The wound ballistics terminology used by Dr. Courtney is non-standard, and thus can be confusing. IMO, there's no need to reinvent the wheel.

The term "PCC" is misleading. Permanent tissue damage (permanent wound) is not limited to the crush mechanism.

"TSC" = "stretch" is redundant. It's redundant because the tissues stretch and rebound - hence "temporary." "Temporary cavity (TC)" is the standard term.

Not sure what is meant by the term "pressure wave."

[Michael Courtney]

Yes indeed, they are incorrect. Permanent cavity diameter is larger at the beginning of the wound track and decreases in diameter as velocity decreases.


Is there prior work showing that a .40 Caliber bullet can produce a permanent cavity that is 1.5" in diameter near the entrance and shrinks to 0.58" in diameter near the end? It was my impression that the IWBA idea is that the bullet has to physically impact the tissue to cause damage, so the damage is limited to the actual diameter of the bullet at that point in the wound tract. Correct me if I am wrong, but doesn't _Handgun Wounding Factors and Effectiveness_ say,

"The tissue disruption caused by a handgun bullet is limited to two mechanisms. The first, or crush mechanism is the hole the bullet makes passing through the tissue. The second, or stretch mechanism, is the temporary cavity formed by the tissues being driven outward in a radial direction away from the path of the bullet. Of the two, the crush mechanism, the result of permanent cavity and penetration, is the ONLY handgun wounding mechanism which damages tissue."

So, the IWBA viewpoint seems to be that the only way for a handgun bullet to damage tissue is to crush it by direct contact. Thus, the diameter of the permanent cavity cannot exceed the diameter of the bullet as it passes a given point along the wound channel. If the maximum diameter of the bullet exceeds the final recovered diameter because the bullet erodes a bit, then the permanent cavity diameter can also decrease. But this isn't a very large difference, and if I recall correctly, it is a common and accepted practice for JHP handgun bullets to estimate the permanent cavity volume as the recovered frontal area of the bullet times the penetration depth.


The wound ballistics terminology used by Dr. Courtney is non-standard, and thus can be confusing. IMO, there's no need to reinvent the wheel.

The term "PCC" is misleading.


I picked up the term "Permanent Crush Cavity" at the Firearmstactical.com web site.

http://www.firearmstactical.com/briefs10.htm



Permanent tissue damage (permanent wound) is not limited to the crush mechanism.


This seems to contradict the excerpt from _Handgun Wounding Factors and Effectiveness_ quoted above.


"TSC" = "stretch" is redundant. It's redundant because the tissues stretch and rebound - hence "temporary." "Temporary cavity (TC)" is the standard term.


Once again, I found the term in use at the Firearmstactical.com web site.

http://www.firearmstactical.com/tacticalbriefs/volume4/number1/article412.htm
http://www.firearmstactical.com/tacticalbriefs/volume4/number1/article414.htm

Let's face it, the firearmstactical site pretty uniformly ascribes the "crush" mechanism to the "Permanent Cavity" thus calling it the "Permanent Crush Cavity" is simply addng the mechanism to the name. Likewise the stretch mechanism is uniformly assigned to the "Temporary Cavity" thus "Temporary Stretch Cavity" is simply adding the mechanism to the name. The terms "Permanent Crush Cavity" and "Temporary Stretch Cavity" are standard and commonly used substitutes for "Permanent Cavity" and "Temporary Cavity" and everyone in the field knows what one means whichever term is used.


Not sure what is meant by the term "pressure wave."

Any time there is a dynamic force applied to a viscous or visco-elastic medium, a pressure wave is created. From a physics viewpoint, this is the pressure supplying the force which expands and decelerates the bullet. The wave propagates outward in all directions from the point of contact between the visco-elastic meduim and the bullet.

The scientific debate revolves around whether the pressure wave contributes to wounding and incapacitation. The Fackler/IWBA opinion is that neither the pressure wave nor the temporary stretch cavity reliably contribute to wounding or incapacitation via handgun bullets.

The pressure wave magnitude can be accurately predicted from applying 1st year college Physics to standard parameters measured from shooting bullets into ballistic gelatin. These kind of predictions can be confirmed by instrumenting ballistic gelatin with a high-speed PZT-based or strain gage-based pressure transducer connected to a high-speed data acqusition system such as a digital oscilloscope. This instrumentation is very similar to that used to measure the transient pressure impulse present inside a gun chamber and barrel.

A more widely accessible method to get a rougher view of a ballistic pressure wave is to shoot a block of ballistic gelatin sitting on a force plate (similar to a digital scale with a very fast response). The force plate measures the instantaneous downward force of the gelatin block. The bullet creates a pressure wave in the block. The pressure wave radiates outward from the bullet path in all directions. When the pressure wave hits the interface between the block and the plate, the pressure wave exerts a downward force on the plate which can be recorded with a digitial oscilloscope or other analog to digital converter.

A more visual (but less scientific) manner to view the pressure wave is to view it's effect when shooting fruit. In short, when you shoot a watermelon, it explodes due to the outward force of the pressure wave.

Michael Courtney

[RecoilRob]

I have been following this thread and it has me wondering a couple of things.

1350fps for a sabot muzzle loader is really, really slow. As you stated the velocity as 'approximate' is there a possibility that it could have been higher? Was the gun and load ever run over a chrono and what was the gun/load combo?

1350fps is about the max muzzle velocity attainable in the .40 and will be substantially higher than any reasonable impact velocity short of a contact wound. Would 100fps reduce the wounding effect to what the 'books' say is normal for the round?

Finally, not being up on my Deer Anatomy, is deer flesh the same as human when comparing wounds?

Not saying that what you observed isn't accurate. I believe every word but also believe what Fackler and company have produced over the years and am just searching for a reasonable explanation to allow both to exist in harmony.

[Michael Courtney]

I have been following this thread and it has me wondering a couple of things.

1350fps for a sabot muzzle loader is really, really slow. As you stated the velocity as 'approximate' is there a possibility that it could have been higher? Was the gun and load ever run over a chrono and what was the gun/load combo?


The impact velocity was estimated from the muzzle velocity (1800 FPS), the ballistic coefficient (0.093), and the measured distance from muzzle to impact (65 yards). I have no reason to doubt the reported muzzle or impact velocity, but being a scientist, I intend to double check these. I am in possession of the gun, powder, and identical samples of bullet and sabot, and I intend to double check the muzzle velocity at the stated powder charge. I'd rather not list the powder charge, because each gun/powder/load combination is a law unto itself and the chronograph gives a much more accurate velocity than can be inferred from the powder charge. However, I've seen comparable powder charges in other muzzleloaders give comparable and even lower velocities. I also intend to do time of flight measurements to confirm the published ballistic coefficient.


1350fps is about the max muzzle velocity attainable in the .40 and will be substantially higher than any reasonable impact velocity short of a contact wound. Would 100fps reduce the wounding effect to what the 'books' say is normal for the round?


Double Tap lists this bullet at 1375 FPS from a 4.0" barrel and 1420 FPS from a 4.5" barrel in their .40 S&W load. Most gun fights occur at ranges where the impact velocity will still be at or above 1350 FPS. Even at a muzzle velocity of 1375 FPS, the impact velocity doesn't drop to 1250 FPS until beyond 20 yards. There aren't many gun fights at this range.



Finally, not being up on my Deer Anatomy, is deer flesh the same as human when comparing wounds?


As far as we can tell, it is comparable. 10% Ballistic Gelatin accurately predicts penetration depths, bullet expansion, and retained mass in both humans and deer. In cases where we have directly observed deer wounding and detailed descriptions are available for the same bullet in humans, our observations in deer agree with the descriptions in humans.


Not saying that what you observed isn't accurate. I believe every word but also believe what Fackler and company have produced over the years and am just searching for a reasonable explanation to allow both to exist in harmony.

There aren't many JHP handgun loads that produce pressure wave levels of this magnitude. I don't know how many "Fackler and company" have looked at, but I haven't found any detailed descriptions of wounding caused by this bullet.

Michael Courtney

[RyanM]

According to my calculations (based on lines of best-fit, based on data exclusively from "Facklerite" sources), a 135 gr bullet at 1350 fps which expands to .58" will crush an average diameter of .52", have a maximum temporary cavity of 3.1", and the resulting wound will have an average diameter of about .86" due to the temporary cavity's stretching. It does sound like the amount of damage you describe is easily explained by the temporary cavity, particularly because my data is based on pig buttock and thigh muscle, which is substantialy stronger than lung tissue.

The hemmoraging in a 5" area is easily explained by blunt trauma. Blunt trauma and tissue stretching are the mechanisms through which the temporary cavity injures. Naturally, the amount of bruising (in the form of bloodshot meat, before the blood clots and darkens) will extend beyond the temporary cavity. If you strike living soft tissues with a hammer, the bruise will extend beyond the tissue directly contacted by the hammer, and beyond the extent to which tissue is displaced by the blow.

[Michael Courtney]

According to my calculations (based on lines of best-fit, based on data exclusively from "Facklerite" sources), a 135 gr bullet at 1350 fps which expands to .58" will crush an average diameter of .52", have a maximum temporary cavity of 3.1", and the resulting wound will have an average diameter of about .86" due to the temporary cavity's stretching. It does sound like the amount of damage you describe is easily explained by the temporary cavity, particularly because my data is based on pig buttock and thigh muscle, which is substantialy stronger than lung tissue.


Would you be kind enough to cite the specific "Facklerite" sources to which you refer. I have been under the impression that the Facker/IWBA viewpoint is that the crush mechanism is the only handgun wounding mechanism which damages tissue. An oft cited reference to support this assertion is

From _Handgun Wounding Factors and Effectiveness_

"The tissue disruption caused by a handgun bullet is limited to two mechanisms. The first, or crush mechanism is the hole the bullet makes passing through the tissue. The second, or stretch mechanism, is the temporary cavity formed by the tissues being driven outward in a radial direction away from the path of the bullet. Of the two, the crush mechanism, the result of permanent cavity and penetration, is the ONLY handgun wounding mechanism which damages tissue."

If this position has been retracted (as it seems it must have from your opening paragraph), it is an interesting development that should be more widely communicated.


The hemmoraging in a 5" area is easily explained by blunt trauma. Blunt trauma and tissue stretching are the mechanisms through which the temporary cavity injures. Naturally, the amount of bruising (in the form of bloodshot meat, before the blood clots and darkens) will extend beyond the temporary cavity. If you strike living soft tissues with a hammer, the bruise will extend beyond the tissue directly contacted by the hammer, and beyond the extent to which tissue is displaced by the blow.

And how do blunt force trauma mechanisms damage tissue beyond that which is contacted directly? The force is transmitted through the tissue via a pressure wave.

Michael Courtney

[ghost squire]

I never interpreted what Fackler and his followers said to exclude temporary cavity as a wounding mechanism. Although that specific document does say that exact thing, which confuses me. What I always thought it meant is that while some cartridges can create significant permanent tissue damage outside of the direct path of the bullet, typical service cartridges cannot do this reliably through thick layers of clothing and after passing through say an arm, then the sternum which guards the heart, and then after an inch or two of flesh that is in front of the heart.

At 1500 FPS or higher I certainly expect the bullet to do this, and considering that the muzzle velocity was 1800 FPS and the animal shot at 65 yards, is it at all possible that you underestimated the impact velocity? Just asking

I will leave this up to the experts such as Shawn Dawdson though.

And until someone takes a human sternum, puts it in front of a deer and dresses that deer in a leather jacket and puts a human arm in front of that, maybe we won't know!

[RyanM]

I meant sources of plain, raw data. My equation for determining amount of stretching/tearing due to temporary cavitation was derived from both my temporary cavity equation, and from Fackler's paper "A reconsideration of the Wounding Mechanism of Very High Velocity Projectiles - Importance of Projectile Shape."

And what evidence do you have that it is the "pressure wave" that causes bruising, as opposed to stress transmitted via tissue compression?

[Michael Courtney]

And what evidence do you have that it is the "pressure wave" that causes bruising, as opposed to stress transmitted via tissue compression?


None. I don't believe there is an important distinction.

Biomechanics does not distinguish between pressure and stress in visco-elastic media such as living tissue. Pressure is force per unit area in a fluid (viscous) medium. Stress is force per unit area in a solid (elastic) medium. The concepts blur in media such as tissue that have both viscous and elastic properties. If one prefers to label the mechanism I am describing as a "stress wave" (transmitted by tissue compression) rather than a pressure wave, we would be describing the same thing by different terminology. The point is that the pressure/stress wave is capable of transmitting a force throughout the medium.

Michael Courtney

[Michael Courtney]

I meant sources of plain, raw data. My equation for determining amount of stretching/tearing due to temporary cavitation was derived from both my temporary cavity equation, and from Fackler's paper "A reconsideration of the Wounding Mechanism of Very High Velocity Projectiles - Importance of Projectile Shape."


Very nice and interesting. Care to share the data you've harvested and your resulting model? This should probably be published or at least distributed privately to interested parties. (Lest I be tempted to repeat the work independently and publish my own empirical model.)


Michael Courtney

[Michael Courtney]

At 1500 FPS or higher I certainly expect the bullet to do this, and considering that the muzzle velocity was 1800 FPS and the animal shot at 65 yards, is it at all possible that you underestimated the impact velocity? Just asking


I plan to verify this as described above. Nosler gives the bullet a BC of 0.093. The low BC is responsible for our estimate of an impact velocity of 1350 FPS. Nosler's BC is consistent with the shape of the bullet and the sectional density. If the BC is really higher then Nosler claims, it is possible that our estimated impact velocity is too low. On the other hand, Nosler is usually pretty accurate in their reported BC's. I'll be sure to report back here if our estimate of the impact velocity needs to be revised.

Michael Courtney

[Shear_stress]

I am curious how you define "temporary cavitation". Cavitation is caused when a sudden pressure drop forces a fluid to boil at a lower temperature than at atmospheric pressure and/or forces the gases dissolved in a fluid out of solution. It is a transient phenomenon that can cause permanent destruction of tissue.

That said, as far as my limited knowledge of ballistics goes, most handgun bullets do not travel fast enough to make cavitation a dominent wounding mechanism. I could be wrong.

Edited to add: though wound ballistics is not my area of expertise, I can clarify some of the terminology used in this discussion. Pressure and stress share the same units units of force per area, but are not treated the same in continuum mechanics. Typically, pressures are seen as exterior loads that transmit a "surface force", while stress distribution is what is considered inside a body. When we talk about the interior of a body, we usually consider stress, not force or pressure. Also, if we are talking about compressible flow, we can start referring to pressure waves as "shock" waves.

[Michael Courtney]

Pressure and stress share the same units units of force per area, but are not treated the same in continuum mechanics.


What you write is correct for solids, but stress is a very murky concept for visco-elastic media, and the concept of stress blends with the concept of pressure. I prefer to use the term pressure, because the wave moves outward in all directions as the medium does not support the kind of directionality suggested by a stress tensor.



Typically, pressures are seen as exterior loads that transmit a "surface force", while stress distribution is what is considered inside a body.


Defining the stress tensor makes sense and is manageable and tractable only in solids. In visco-elastic media pressures of this magnitude behave as pressures (rather than stress) in that the pressure is the same in all directions and you cannot define a stress tensor.


When we talk about the interior of a body, we usually consider stress, not force or pressure. Also, if we are talking about compressible flow, we can start referring to pressure waves as "shock" waves.


In the regions where the visco-elastic medium is behaving more like a fluid (not supporting a shear), it is more appropriate to consider pressure rather than stress. Calling the wave a "shock" wave has a lot of negative baggage in the field of terminal ballistics, so I have avoided this designation.

Michael Courtney

[Shear_stress]

The terminology used in continuum mechanics are derived independent of the material.

If the pressure is the same in all directions, you definately can define a stress tensor. This is simply the case when your three principle stresses are equal. What you can't define is a principle direction, and that is only because you have an infinite number of them at that point within the body.

Also, pressure is equal in all directions in hydrostatics, but is not the case when you have a moving pressure wave.

[Michael Courtney]

Also, pressure is equal in all directions in hydrostatics, but is not the case when you have a moving pressure wave.

It is possible to have a pressure wave that does not move equally in all directions, but we believe that the pressure wave radiates outward nearly equally in all directions for most bullet designs. One of the questions we hope to investigate is whether an anisotropic pressure wave would enhance wounding or incapacitation by focussing the energy of the wave in preferred directions like a directional gain antenna focusses an RF wave in preferred directions.

Michael Courtney

[Michael Courtney]

Also, pressure is equal in all directions in hydrostatics, but is not the case when you have a moving pressure wave.

It is possible to have a pressure wave that does not move equally in all directions, but we believe that the pressure wave radiates outward nearly equally in all directions for most bullet designs. One of the questions we hope to investigate is whether an anisotropic pressure wave would enhance wounding or incapacitation by focussing the energy of the wave in preferred directions like a directional gain antenna focusses an RF wave in preferred directions.

Michael Courtney

[Shear_stress]

pressure wave radiates outward nearly equally in all directions for most bullet designs

Hi Michael.

A pressure wave will radiate equally in all directions like a ripple in a pond, but this does not mean a hydrostatic condition. Also, the factors that affect the intensity of the pressure wave (bullet velocity and geometry, for example) change constantly as the bullet slows down and deforms. Add to this the nonlinear properties of human tissue, and you've got a doozy of a problem to solve.

[Michael Courtney]

Double post, sorry.

[Michael Courtney]

Hi Michael.

A pressure wave will radiate equally in all directions like a ripple in a pond, but this does not mean a hydrostatic condition. Also, the factors that affect the intensity of the pressure wave (bullet velocity and geometry, for example) change constantly as the bullet slows down and deforms. Add to this the nonlinear properties of human tissue, and you've got a doozy of a problem to solve.

The technical details do get tricky at this level of analysis. I appreciate your suggestions. We should consider calling the effect a "stress wave" rather than a pressure wave.

Fortunately, the main point of the stress/pressure wave is that the effects of a bullet can be transmitted beyond the reach of the stretch and crush cavities, and this can be seen on the phenomenological side without developing a finite element model from the ground up.

Thanks,

Michael Courtney

[RyanM]

So you're referring to a pressure wave that is caused by the temporary cavity, rather than the sonic pressure wave? That's completely different, and may indeed be a significant source of ballistic trauma in some cases, though the vast majority of handgun cartridges do not cause a very substatial temporary cavity.

I can give you my equation, but unfortunately I cannot make available all the necessary equations to calculate the temporary cavity, until and unless I get word back from Duncan MacPherson about whether he would mind me distributing a spreadsheet calculator which makes use of his equations.

[ impact velocity (fps) / cavitation threshold velocity (fps) ]^2 * bullet weight (grains) / 37.85 (constant) - permanent cavity volume

If the impact velocity is between the cavitation threshold and 2 * cavitation threshold, multiply the result by

velocity / cavitation threshold - 1

If velocity is under the cavitation threshold, there is no temporary cavity beyond the diameter of the bullet. If it's over 2 * threshold, use the first equation unmodified.

That set of equations gives you the volume of the temporary cavity in cubic inches. The cavitation threshold velocity must be determined using one of Mr. MacPherson's equations. It's around 400-700 for most bullets.

To determine the diameter of the temporary cavity at the widest point, the most accurate method I've found (which is not overly complex) is

2 * sqrt[ temporary cavity volume (in^3) * 3 + permanent cavity volume (in^3) / pi / penetration depth (in) ]

Permanent cavity volume and penetration depth in my spreadsheet are both also derived from MacPherson's equations. This equation assumes the volume of the temporary and permanent cavities is in the form of a cone, and gives you the diameter of the base of the cone. It's not 100% accurate, but it's "good enough for government work."

The permanent stretch equation is much easier. If the temporary cavity is under 8", it's

0.5 * temporary cavity max diameter - 0.5

If it's over 8", then

1.45 * temporary cavity max diameter - 8.1

Whichever equation you use, if the impact velocity is under 2,500 fps, multiply the result by

striking velocity / 2,500

If striking velocity is over 2,500, just use that result. This assumes that the projectile does not fragment.

If it does fragment, then add the results of this second equation. I am much less certain of the accuracy of this one, however. In this case, fragmentation means the "normal" type of fragmentation which high-powered rifle softpoints produce; a main bullet mass and many, many, tiny fragments.

0.02961687062 * fragmentation percent (integer; i.e. 30% = 30.0) + 0.0000702724359 * fragmentation percent^2 - 0.00001961028555 * fragmentation percent^3 + 0.0000002693036131 * fragmentation percent^4 - 0.000000001073717949 * fragmentation percent^5 * (0.00025 * striking velocity - 0.25) * temporary cavity diameter

If striking velocity is under 1,000 fps, then assume that there is no extra tearing at all due to the perforation of tissues.

As examples, here are the results for a few bullets:

150 grain .308 striking at 2500 fps, expanding to 0.60", with 20% fragmentation:
penetration, 15.3"
volume of tissue crushed, 3.2 in^3
avg. diameter crushed, 0.55"
max temporary cavity, 5.4"
max permanent cavity, 3.8" (in muscle, more in lungs)

The exact same bullet with no fragmentation produces:

penetration, 18.6"
volume of tissue crushed, 4.0 in^3
avg. diameter crushed, 0.55"
max temporary cavity, 5.5"
max permanent cavity, 2.8" (in muscle, more in lungs)

9mm 124 grain hollowpoint striking at 1100 fps, expanding to 0.55"

penetration, 13.3"
volume of tissue crushed, 2.4 in^3
avg. diameter crushed, 0.52"
max temporary cavity, 2.5"
max permanent cavity, 0.57" (in muscle, more in lungs)

edit: mistake in an equation

[ghost squire]

I'll be sure to report back here if our estimate of the impact velocity needs to be revised.


Excellent, and I for one would like to thank you for your work.

[benEzra]

Very interesting work, sir. Thank you for sharing it.

[Michael Courtney]

So you're referring to a pressure wave that is caused by the temporary cavity, rather than the sonic pressure wave? That's completely different, and may indeed be a significant source of ballistic trauma in some cases, though the vast majority of handgun cartridges do not cause a very substatial temporary cavity.


By "pressure wave" I mean everything a high-speed pressure gauge would measure. One can insert a high-speed PZT-based or strain-based pressure gauge into ballistic gelatin and measure this pressure wave. The pressure wave includes the sonic pressure wave, but has different components as well.

So you're referring to a pressure wave that is caused by the temporary cavity, rather than the sonic pressure wave?


I would tend to consider the TSC an effect rather than a cause of the pressure wave. Pushing tissue aside requires a force, and a force applied over an area is a pressure. If there were no pressure, there would be no force, and the tissue would not be moved from it's initial static (rest) condition. Of course, once the tissue reaches its maximum displacement, the elastic force restores the tissue which increases the duration of the pressure wave as it bounces around, so in some sense the TSC contributes because the elasticity of the stretched tissue provides a restoring force.

The volume of the TSC is highly correlated with the peak pressure magnitude, so there is a very close relationship.

In experiments using 10-20 lb mammals immersed in water, we were able to incapacitate the test subject with near misses fired into the water 1-2" from the chest and neck area of the test subject. The idea was to transmit a pressure wave from the water to the chest and neck area of the test subject without a temporary stretch cavity or a permanent crush cavity even being present.

We have an experiment on the drawing board to apply a pressure wave into a goat/deer/sheep-sized test subject via a cannula connecting an external saline filled bladder to the carotid or femoral artery. Shooting the saline bladder would transmit a pressure wave into the artery. There are some technical challenges we are working through.

We have another experiment on the drawing board to shoot test subjects with two bullets nearly simultaneously and study how wounding and incapacitation vary with a small delay between the bullet impacts. Since the pressure wave of the two bullets will add by the principle of superposition, observing how this enhances the wounding and incapacitation effects should suggest whether it is the early (sonic and shock) or later (TSC-related) components of the pressure wave making the greater contribution. In other words, the idea is to study wounding (volume of destroyed tissue, volume of moderate to severe hemorrhaging) and incapacitation (average distance run after the shot in deer, or average incapacitation time in goats, pigs, or sheep) vary as the delay between the bullets is varied from zero to 100 ms.

At zero delay, we expect maximum superposition of the pressure waves. This should lead to an estimated wounding enhancement of 40% (compared to 100 ms delay) and an estimated incapacitation enhancement of 20% (compared to 100 ms delay). As the delay between bullet impact is increased from 0 ms to 100 ms, the wounding/incapacitation enhancement should decrease. The delay values where the wounding/incapacitation enhancement shows a sudden drop suggests the more important component of the pressure wave. If the enhancement drops markedly within the first 10 ms, this suggests the sonic and leading shock wave play an important role, because the TSC-related wave follows later. If the enhancement does not drop markedly until longer delay times, this suggests that either the sonic and leading shock wave have a longer than expected reverberation time, or that the TSC-related wave plays the more important role.

Both of these future experiments are considerably more expensive than the work we have done to date, and carrying them out will require acquisition of adaquate funding.

Michael Courtney

[Michael Courtney]

I can give you my equation . . .

Thank you very much.

Michael Courtney

[Shear_stress]

Hi Michael,

Please clarify the following:



In experiments using 10-20 lb mammals immersed in water, we were able to incapacitate the test subject with near misses fired into the water 1-2" from the chest and neck area of the test subject. The idea was to transmit a pressure wave from the water to the chest and neck area of the test subject without a temporary stretch cavity or a permanent crush cavity even being present.

First, how exactly did you carry out this experiment? How did you determine if the 10-20 lb mammal was incapacitated? Are you sure it wasn't just because you were holding an air-breathing animal underwater?

Second, how would the results of this experiment be applicable to a study of internal wounding on humans?

It would be easier if you could just tell us where we can find a copy of the journal article.

Thanks!

[Shawn Dodson]

Dr. Courtney writes: It was my impression that the IWBA idea is that the bullet has to physically impact the tissue to cause damage, so the damage is limited to the actual diameter of the bullet at that point in the wound tract. Untrue. The temporary cavity is known to damage tissues, even resilient ones, when the strain placed upon them stresses the tissues beyond their elastic limits.

Correct me if I am wrong, but doesn't _Handgun Wounding Factors and Effectiveness_ say… So we’re not mixing apples & oranges, let me clarify that HWFE is not an “IWBA” document.

So, the IWBA viewpoint seems to be that the only way for a handgun bullet to damage tissue is to crush it by direct contact. Thus, the diameter of the permanent cavity cannot exceed the diameter of the bullet as it passes a given point along the wound channel. If the maximum diameter of the bullet exceeds the final recovered diameter because the bullet erodes a bit, then the permanent cavity diameter can also decrease. But this isn't a very large difference, and if I recall correctly, it is a common and accepted practice for JHP handgun bullets to estimate the permanent cavity volume as the recovered frontal area of the bullet times the penetration depth.

The IWBA viewpoint includes the concept of “reliable,” as in “reliable tissue damage.”

You describe the entry wound as, “pulverized a large (1.5” diameter) on the inside of the rib cage and in the liver….” I wouldn’t be surprised if the bullet had expanded 180-200% (.72 - .80 caliber) at this point along the wound track. It probably was also beginning to shed fragments.

The increased damage I observe on the exit (interior) side of the thoracic wall, as shown in your photo, is consistent with permanent disruption caused by the temporary cavity. As the bullet penetrated the wall of the thorax it expanded in the musculature between the ribs. The ability of the rib muscle to stretch was limited by its relatively short length as well as being attached to rib bones. In essence the wounding effect of the temporary cavity produced a sort of cone-like “beveled” wound in the wall of the thorax – the entrance wound was small and the exit wound (on the inside of the rib cage) was substantially larger in diameter because it could not tolerate stretching. In effect, the wound track through the rib muscle was short and the exit side was burst open by the temporary cavity.

Indeed, all the increased damage you observed is caused by the temporary cavity. The tissues are located along the wound track where the diameter of the temporary cavity is greatest.

If one stops to consider that the temporary cavity is, in essence, blunt force trauma delivered at 1/10th bullet velocity, then might be able to imagine the amount of violent force involved.

As velocity decreases with penetration soft tissues have time to move out of the bullet’s way – instead of being crushed by the oncoming bullet the tissues have time to stretch around the bullet as it passes through. This decreases the diameter of the permanent cavity. Thus the “effective permanent cavity” is larger in diameter at the beginning of the wound track.

It is common *FBI practice* to estimate permanent cavity volume in the manner you describe, for comparative purposes. Fackler may have done it at one time, although off the top of my head I’m unaware that he ever did. To the best of my knowledge, Fackler/IWBA have never been concerned about the *volume* of the permanent cavity – just how deep and how big?

I picked up the term "Permanent Crush Cavity" at the Firearmstactical.com web site. Indeed you did. In the context of shotgun pellets, spherical shot, propelled at typical shotgun velocities, produce a crush injury.

Let me apologize, however, for using the term “permanent wound” in my earlier post when I should have said “permanent disruption.” Permanent disruption includes damage produced in soft tissues by the temporary cavity.

Here are terms I use and what they mean (my understanding has evolved and matured with time, so I won’t be surprised if you find past inconsistencies):

Permanent cavity – the hole crushed by the bullet.
Temporary cavity – the tissues that are violently shoved aside by the passing bullet.
Permanent disruption – all permanent tissue damage caused by permanent cavity, temporary cavity and fragmentation.

This seems to contradict the excerpt from _Handgun Wounding Factors and Effectiveness_ quoted above. HWFE also states: “All handgun wounds will combine the components of penetration, permanent cavity, and temporary cavity to a greater or lesser degree.” Therefore, the effects vary due to the characteristics of the particular projectile when it hits, as well as the characteristics of the tissues involved and their location along the wound track in relation to the wounding components.

Once again, I found the term [temporary stretch cavity] in use at the Firearmstactical.com web site. The cited documents are a product of the former U.S. Immigration and Naturalization Service, which are somewhat verbose.

Any time there is a dynamic force applied to a viscous or visco-elastic medium, a pressure wave is created. From a physics viewpoint, this is the pressure supplying the force which expands and decelerates the bullet.
……….
A more visual (but less scientific) manner to view the pressure wave is to view it's effect when shooting fruit. In short, when you shoot a watermelon, it explodes due to the outward force of the pressure wave. The explosive effect is produced by the temporary cavity; therefore your “pressure wave” is, in fact, the temporary cavity, which follows in the wake of the passing bullet.

[Shawn Dodson]

Dr. Courtney writes: Pushing tissue aside requires a force... Indeed, inertial force.

[Shear_stress]

Shawn,

Considering Michael's shifting terminology, his incomplete grasp of continuum mechanics (which is a cornerstone of biomechanics), and his references to unpublished studies of dubious experimental value, I am not convinced he is the real deal.

[Michael Courtney]

Shawn,

Considering Michael's shifting terminology, his incomplete grasp of continuum mechanics (which is a cornerstone of biomechanics), and his references to unpublished studies of dubious experimental value, I am not convinced he is the real deal.

I freely admit that I am not the Biomechanics expert in our research group. We have a scientist with a PhD in Biomechanical Engineering from Harvard University on our team who grasps certain issues more completely than I do.

My PhD is in Physics (from MIT), and my areas of specialty are wave propagation, statistics, and pressure measurement.

Here is a list of my publications:

Michael Courtney and Daniel Kleppner, Physical Review A 53, 178 (1996)

Michael Courtney, Chaos 6, 1 (1996).

Michael Courtney, Physical Review A 51, 4558 (1995).

John A. Shaw, John B. Delos, Michael Courtney and Daniel Kleppner, Physical Review A 52, 3695 (1995).

Michael Courtney, Hong Jiao, Neal Spellmeyer, Daniel Kleppner, Jing Gao and J.B. Delos, Physical Review Letters 27, 1538 (1995)

Michael Courtney, Hong Jiao, Neal Spellmeyer and Daniel Kleppner, in the proceedings of the 4th Drexel Symposium on Quantum Nonintegrability (1995).

Michael Courtney, Neal Spellmeyer, Hong Jiao and Daniel Kleppner, Physical Review A 51, 3604 (1995).

Michael Courtney, Hong Jiao, Neal Spellmeyer and Daniel Kleppner, Physical Review Letters 73, 1340 (1994)

B.D. Simons, A. Hashimoto, M. Courtney, D. Kleppner and B.L. Altshuler, Physical Review Letters 71, 2899 (1993)

G. Chanmugam, P.E. Barrett, Kinwah Wu and M.W. Courtney, Astrophysical Journal Supplement Series 71, 323 (1989)

L.F. DiMauro, Dalwoo Kim, M.W. Courtney and M. Anselment, Physical Review A 38, 2338 (1988)

Michael Courtney

[Michael Courtney]

Hi Michael,

First, how exactly did you carry out this experiment? How did you determine if the 10-20 lb mammal was incapacitated? Are you sure it wasn't just because you were holding an air-breathing animal underwater?


After the shot, the mesh confining the test subject was removed, and the animal was determined to be incapacitated if it failed to run a distance of 20' in one minute. Some of the test subjects were killed instantly, and there were no determinations of incapacitation that were even close. Either the test subject was completely immobile or barely able to move, or it was off to the faces and past 20' in under 5 seconds.

The test subjects were confined in such a way that they could breath by holding their heads out of the water. We are also certain that other aspects of our experimental design wer not causing incapacitation because the 147 grain 9mm WWB load repeatedly failed to cause incapacitation in numerous attempts. This load creates a much smaller pressure wave than the other loads we tested that produced incapacitation.


Second, how would the results of this experiment be applicable to a study of internal wounding on humans?


We're not adherents to the presupposition that incapacitation can only occur by wounding that is easily detectable to a trauma surgeon or medical examiner. Our goal in this experimental design was to see if a ballistic pressure wave could incapacitate mammals without any wound channel present. This idea is important when considering whether humans might experience incapacitation via effects of the pressure wave acting beyond the wound channel. It's not proof, of course, but the demonstration of a biological effect in live animals of this side is useful for indicating that humans probably experience a similar effect.


It would be easier if you could just tell us where we can find a copy of the journal article.
Thanks!


A report is currently in preparation for publication. This experiment is described along with the results of two related projects. We are limited by a non-disclosure agreement not to distribute pre-publication copies, but we can email or post the current copy of the abstract.

Michael Courtney

[Shear_stress]

The most recent publication date you list is from 1996 and the subjects of these papers seem to be biased toward particle or quantum physics.

A report is currently in preparation for publication. This experiment is described along with the results of two related projects. We are limited by a non-disclosure agreement not to distribute pre-publication copies, but we can email or post the current copy of the abstract.

Well, if your group is as capable as you say, it should have a list of recent publications that you can reference. Also, what is the name of your research group? Where is it located? Also, please post the website of your research group. A Google search turns up nothing.

Michael Courtney may exist, but that doesn't mean you are him.

[Michael Courtney]

Untrue. The temporary cavity is known to damage tissues, even resilient ones, when the strain placed upon them stresses the tissues beyond their elastic limits.


Thanks for taking the time and effort to answer.

I had been under the impression that the IWBA position was that this only occurs for rifle bullets, and I believe I've read in multiple Fackler publications that the temporary cavity is not a reliable source of wounding via handgun bullets. It seems that there has been an evolution in understanding. Thanks for helping bring me up to date.


So we’re not mixing apples & oranges, let me clarify that HWFE is not an “IWBA” document.


Thanks. I guess I was considering most of the stuff favorably referenced on the firearmstactical web site to represent IWBA viewpoints.


You describe the entry wound as, “pulverized a large (1.5” diameter) on the inside of the rib cage and in the liver….” I wouldn’t be surprised if the bullet had expanded 180-200% (.72 - .80 caliber) at this point along the wound track. It probably was also beginning to shed fragments.


That is my thinking also.


Indeed, all the increased damage you observed is caused by the temporary cavity. The tissues are located along the wound track where the diameter of the temporary cavity is greatest.


I agree that one cannot ascribe the pulverized tissue to the pressure wave independently of the temporary cavity because they occur in the same region. However, we do observe less severe wounding in areas seemly beyond the reach of the temporary cavity, specifically the minor hemorrhaging of the muscle tissues on the abdominal wall and rib cage opposite the entrance wound and the more severe hemorrhaging around the entry wound (aka bloodshot meat).

We've also seen major hemorrhaging in unborn fetuses of does shot broadside through the center of the chest with the 125 grain Triton Quik-shok at 1450 FPS. This is far beyond the reach of the temporary cavity. We've never seen this hemorrhaging with low pressure wave projectiles. We believe that the pressure wave that originates at the center of the chest is focussed by the approximately ellipsoidal shape of the thoracic cavity and hits the fetus pretty hard.


If one stops to consider that the temporary cavity is, in essence, blunt force trauma delivered at 1/10th bullet velocity, then might be able to imagine the amount of violent force involved.


Sure, but the pressure wave delivers blunt force trauma also, and it can deliver it beyond the reach of the temporary cavity.


Here are terms I use and what they mean (my understanding has evolved and matured with time, so I won’t be surprised if you find past inconsistencies):

Permanent cavity – the hole crushed by the bullet.
Temporary cavity – the tissues that are violently shoved aside by the passing bullet.
Permanent disruption – all permanent tissue damage caused by permanent cavity, temporary cavity and fragmentation.


Thanks for taking the time to explain. My understanding is evolving to, and I am grateful for your assistance in this process.


The explosive effect is produced by the temporary cavity; therefore your “pressure wave” is, in fact, the temporary cavity, which follows in the wake of the passing bullet.

As I wrote before, the temporary cavity is the tissue response to an applied force via the pressure wave. The leading edge of the pressure wave has passed, and the movement of the tissue follows. The volume of the temporary cavity is thus highly correlated with the magnitude of the pressure wave. However, the pressure wave extends well beyond the reach of the temporary cavity, as described above. We believe this has important consequences for both wounding and incapacitation.

Michael Courtney

[Michael Courtney]

Well, if your group is as capable as you say, it should have a list of recent publications that you can reference. Also, what is the name of your research group? Where is it located? Also, please post the website of your research group. A Google search turns up nothing.

A significant part of science is public disclosure.

The Ballistic Testing Group has been active since 2001. The abstract I mentioned is for our first publication which is in preparation. We are under a non-disclosure agreement which prevents release of a certain other information prior to publication. One motive for retaining a degree of privacy at this point is to minimize interference from animal rights activists. We believe that after certain information is disclosed we will encounter a much larger rate of interference by animal rights extremists.

Check out the article on page 10 of the December 2005 American Rifleman.

A couple of quotes:

"PETA wants to stop medical advancements that use animal research in any way."

"PETA's agenda is being forced upon society with acts of violence and terrorism . . . This eco-terrorism movement is so dangerous, the FBI has declared it America's No. 1 domestic terrorist threat on American soil . . . Scientists, doctors and their families are having property destroyed and are getting hate mail, letters loaded with razor blades and rat poison, and death threats and bomb threats."

Separate local efforts to kill some of our overpopulated deer herd have met with expensive legal challenges from these people. Hunters at a nearby farm endured multiple instances of vandalism, harassment, and intimidation for each of the last 5 years. I was personally threated in an anonymous phone call. Some of the contributors to our research effort have understandably chosen to remain anonymous even after publication, and we are keeping a lot of information private prior to publication because we believe that the live animal aspects of our work may well be shut down for a time after certain details are released.

Michael Courtney

[Shear_stress]

We've also seen major hemorrhaging in unborn fetuses of does shot broadside through the center of the chest

I'm sorry but your research group is somehow able to obtain unborn fetuses on which to perform gunshot-wound experiments?!

Again, your research group should have a list of recent publications that you can reference. What is the name of your research group? Where is it located? Also, please post a link to its website. A Google search turns up nothing.

Science is about disclosure!

Edited to add: The only reference to a "Ballistic Testing Group" I can find on the internet is a link to another one of your posts on the highroad.org!
Edited to add: There is a lot of controverisal research going on at institutes around the country. But they still publish!
Edited once again: If your research is so risky, than why post on a public forum under what we are led to believe is your own name?

[Michael Courtney]

I'm sorry but your research group is somehow able to obtain unborn fetuses on which to perform gunshot-wound experiments?!


We shot female deer in a normal (but carefully controlled)hunting-type of situation at a time of year when some test subjects happened to be pregnant. The discovery of severe hemorrhaging of the unborn fetuses was unintentional and accidental, yet we believe that our interpretation of this wounding as a consequence of the pressure wave is valid.


Science is about disclosure!


Science is about disclosing results and sufficient information for other research groups to repeat those results.

It is very common in live animal research projects not to disclose the location, the identity of some contributors, funding sources, photographs, and other details that might provide a target for or attract undue attention from the animal rights fanatics.

Michael Courtney

[JohnKSa]

Michael,

Please continue to post your results and please don't be discouraged by the argumentative and confrontational responses of some. Unfortunately, many people aren't interested in discovering the truth unless it aligns with their pre-conceived beliefs and notions.

I think I can say with some level of confidence that there are a large number of people reading this thread with great interest.

Thanks,

John

[P95Carry]

there are a large number of people reading this thread with great interest.That's a fact John :) Thx again Michael.

[RecoilRob]

I don't believe that anyone ever said that a tempory cavity or pressure wave cannot damage tissue. What has been (IMO) proven is that only permanent crushing of important tissue can be reliably counted on to incapacitate a human.

Sometimes the temporary cavity produced by lightweight, fast projos will cause an instant shutdown of the attacker......but manytimes it has not. Repeatedly.

A properly placed, deep penetrating bullet of modest velocity will end all arguments in a fight. Everytime.

And, for the sake of argument, sonic shockwaves can and have done major tissue damage to persons around very loud jet and rocket engines. That is why no-one is allowed near the Shuttle when it launches. They would be injured or killed by the sound alone.

[Michael Courtney]

What has been (IMO) proven is that only permanent crushing of important tissue can be reliably counted on to incapacitate a human.

Sometimes the temporary cavity produced by lightweight, fast projos will cause an instant shutdown of the attacker......but manytimes it has not. Repeatedly.

A properly placed, deep penetrating bullet of modest velocity will end all arguments in a fight. Everytime.



Good point. But not even "permanent crushing of important tissue can be reliably counted on to incapacitate a human" within the time span of most gun fights. In other words, incapacitation in the 2-5 second time frame of most gun fights is inherently a probabilistic proposition. Whether or not incapacitation eventually occurs is less important than the likelihood of incapacitation within the duration of the gun fight.

Therefore, a more realistic view of what a bullet should do is to provide the highest probability of incapacitation in a very short time frame. This is why I believe the pressure wave is important: it increases the probabality of incapacitation within the time frame of a gun fight.

In my opinion, increasing the probability of incapacitation in the first five seconds is worth the possible decrease in probability of eventual incapacitation.

For example, (for a given shot placement) a bullet which offers a 50% chance of incapacitaion in 5 seconds or less, but only a 70% chance of eventual incapacitation is a better choice than a bullet which offers a 20% chance of incapacitation in 5 seconds or less but has a 99% chance of eventual incapacitation.

Michael Courtney

[RecoilRob]

Somewhere in this or the other related thread Mr. Courtney acknowledges the importance of a deep PCC and this is good. Otherwise, the whole notion of the 'pressure wave' reminds me of the failed RII of the 70's where the TC was held to be the primary incapacitating mechanism and penetration was sacrificed for more TC.

So long as we have deep penetration with corresponding PCC, it does no harm to try to increase the TC. Good luck in your efforts.

[Michael Courtney]

Somewhere in this or the other related thread Mr. Courtney acknowledges the importance of a deep PCC and this is good. Otherwise, the whole notion of the 'pressure wave' reminds me of the failed RII of the 70's where the TC was held to be the primary incapacitating mechanism and penetration was sacrificed for more TC.

So long as we have deep penetration with corresponding PCC, it does no harm to try to increase the TC. Good luck in your efforts.

Thanks.

One goal of our work is to try and quantify the relative merits of the PCC and the pressure wave magnitude in order to help people making ammo choices identify the tradeoffs between the two for their own application and risk assessments. Penetration beyond that needed for an application or risk assessment reduces the pressure wave and the temporary cavity and their potential benefits. To little penetration and neither the PCC, the TC, nor the pressure wave has much effect where needed.

An important result of our work is the recognition that if two different loads create comparable permanent crush cavities and penetration depths, the load with more energy and/or more fragmentation is a better bet to create more rapid incapacitation.

An aspect we haven't talked about much is that the PCC and the pressure wave appear to be largely independent incapacitation mechanisms. In other words, the probability of incapacitating via the PCC and the probability of incapacitating via the pressure wave combine by the rules of probability for independent causal factors. For example, if a load has a 50% chance of causing incapacitation via the PCC in under 5 seconds and a 50% chance of causing incapacitation via the pressure wave in under 5 seconds, the combined probability for incapacitation is 75%.

This seems rather academic until one considers the implications for enhancing the incapacitation probability by independent causal effects. In other words, suppose we are able to add an electrical and/or a drug-related incapacitation mechanism to a bullet with a 75% combined probability of incapacitation via PCC and pressure wave. If the drug-related incapacitation mechanism only works 50% of the time, the total incapacitation probability becomes 87.5%. Now add an electrical incapacitation mechanism. If the electrical incapacitation mechanism only works 50% of the time the total incapacitation probability becomes 93.75%.

Now, the idea of drug-related or electrical incapacitation mechanisms might seem far fetched (and they are!), but they serve to illustrate the point that combining a number of unreliable (50%) incapacitation mechanisms can indeed result in much more reliable incapacitation (93.75%) than commonly observed.

Rather than squeezing more reliable rapid incapacitation from the PCC, the improving the status quo lies in increasing and introducing independent incapacitation mechanisms in future bullet designs.

Michael Courtney

[Borachon]

.40 doesn't penetrate winter jackets

http://www.lineofduty.com/blotterstory.asp?StoryID=73157

[RyanM]

Those were Federal EFMJs, which exhibit a much lower weight and lower velocity than 99% of conventional hollowpoints, much poorer expansion reliability, and have a rubber tip. Not exactly representative of an entire caliber. Even a .22 pistol will shoot through a dozen layers of thick cloth, as long as you're using bullets made of lead.

[Biker]

.40 doesn't penetrate winter jackets

http://www.lineofduty.com/blotterstory.asp?StoryID=73157
Well then, put on your warmest ski-outfit and piss me off. Heh heh...you should be just fine in front of either my G23 or G27.
I'm guessing your post was in jest?
Biker

[Michael Courtney]

I should mention that our motive in our ballistic research is not to benefit any particular gun industry interest, but rather to make our results widely available and easily repeatable so that the appropriate gun industry interests will apply our scientific results to the development of more effective products.

Our interest goes beyond terminal ballistics.

We've got a separate project that shows that reducing barrel friction can increase bullet energy by 100 ft-lbs in service cartridges.

In yet another project we have developed methods for measuring bullet velocity and ballistic coefficients with a PC soundcard to enable more ammunition users to compare manufacturers specifications to the reality of their own guns. We hope that one or more of the chronograph manufacturers will productize this idea.

We are also developing forensic techniques for reconstructing gun fights from audio recordings of the event. With the increasing amount of audio surveillance, an increasing number of shooting events are being recorded. Precise time reconstruction of shooting events should allow for incapacitation theories to be quantitatively tested, so the gun industry interests will have a much better idea which incapacitation theories are accurate in considering future designs.

Michael Courtney

[Borachon]

Well then, put on your warmest ski-outfit and piss me off. Heh heh...you should be just fine in front of either my G23 or G27.

Wouldn't be my first time. But you really need to direct your wrath toward the person who told all those horrible lies about your "wonder weapon". So give those cops up in Michigan a call and tell them that you'd like to meet them in an open field because you're upset about all the lies they told that newspaper reporter. I'm just the messenger.

And oh, by the way, sounds like pissin' you off ain't so hard to do. Me..I've got a short fuse myself. We'd be well-matched.


Point I was trying to make before it got personal, is that you can talk all day (and I have before) about the merits of caliber, bullet weight, type of powder to use, hollowpoint vs FMJ vs Glaser vs frangible and go all the way around the world and still come back to the fact that you are shooting a weapon that no right thinking person would ever consider as their main line of defense in a war. People survive being shot in wars all the time. War rifles are much more powerful than pistols. Talking about which cheesy light-weight pop gun can out perform another cheesy pop gun is moving deck chairs on the Titanic.
Accuracy, economy of movement, familiarity with the performance and maintanence of your pistol. Everything else is chair moving.

[Borachon]

We've got a separate project that shows that reducing barrel friction can increase bullet energy by 100 ft-lbs in service cartridges.

No offense...but you had to do a STUDY to figure that out? Frictionless environments are going to produce faster moving objects...thus increasing energy output because of decreased lost momentum.

Kind of a no-brainer.

[Michael Courtney]

No offense...but you had to do a STUDY to figure that out? Frictionless environments are going to produce faster moving objects...thus increasing energy output because of decreased lost momentum.

Kind of a no-brainer.

It is a no brainer that reducing friction will increase energy, but the important result is quantifying how much the energy can be increased. If reducing barrel friction would only increase bullet energy by 5-10 ft-lbs, I don't think anyone in the gun industry would bother. However, increasing energy by 100 ft-lbs is like stepping up to the next larger cartridge case in a given caliber, and might be significant enough to stimulate development activity.

The gun industry has temporarily plataued in terms of figuring out how to improve incapacitation from a pistol. Personally, I believe that within the next 25 years, we can see new designs that will make pistols as effective in incapacitating as the .223 is today.

Some of the gains in effectiveness will be incremental, such as gaining 100 ft-lbs of additional energy by reducing friction, a bullet that doesn't begin to expand at all until it has penetrated 3" or so (so more energy can be transferred closer to the vital organs, creating a larger pressure wave where it will do the most good), or a bullet design that creates a more intense pressure wave by a focussing effect (like a gain antenna focuses an RF wave).

Other gains in pistol bullet effectiveness will be in more revolutionary techniques, perhaps including:
1. An electrical effect, perhaps charging a capacitor to deliver a good shock on impact, or magnitizing the bullet. A changing magnetic field produces a current in a conducting medium. Body fluids are sufficiently conducting that impact by a magnetic bullet will produce a current.
2. A drug-related effect. This is going to be a hard sell politically, but if a drug can be developped that both provides very rapid incapacitation and increases the ultimate survivability, it may be politically viable, especially if the need is recognized to glean information from terrorists.
3. Explosive bullets designed to explode after penetrating a specified depth. We know exactly how to create TSC's and pressure waves as large as rifle bullets from pistol cartridges, 20 grains of explosive charge will easily do the trick.
4. Bullets that reach rifle velocities by continuing to accelerate after leaving the barrel. Of course, what you're really designing is a little rocket.

Currently, the liability and PR/political issues make these more revolutionary ideas impractical. However, there are only so many terrorist attacks/active shooter situatons that our collective political will can tolerate before we seek to at least arm our police and military with more effective handguns.

Michael Courtney

[carolinaman]

Hi there Mr. Courtney,

I have been reading all of your posts with thoughtful and considerable interest and wish to know if you think that the fnfiveSeven cartridge is quite approaching what you have suggested a "gun industry search for a rifle velocity cartridge in a handgun"?

Best,

Chris

[Michael Courtney]

Hi there Mr. Courtney,

I have been reading all of your posts with thoughtful and considerable interest and wish to know if you think that the fnfiveSeven cartridge is quite approaching what you have suggested a "gun industry search for a rifle velocity cartridge in a handgun"?

Best,

Chris

Apart from penetrating kevlar, rifle velocities are only interesting if you do it with a bullet with enough mass to deliver energy levels comparable to a .223. A 31 grain bullet at 2300 FPS only delivers 364 ft-lbs of energy, which is comparable to a standard velocity 9mm.

We've done some testing in deer with 40 and 55 grain bullets at impact velocities near 2300 FPS, and we don't see anything much different from comparable energy levels from comparable handgun loads at similar penetration (.357 Sig and 10mm).

Crossing some velocity threshold doesn't help if you sacrifice bullet weight to do it. Getting to rifle-type velocities is only going to produce rifle-like incapacitation if you've also got rifle-like energy levels combined with the right penetration depth. In my mind, this begins at about 1000 ft-lbs of energy and 12" of penetration.

Two different bullets with comparable energy levels, penetration depths, and percentage of retained mass are likely to produce comparable incapacitation even if they differ greatly in velocity, mass, and/or diameter.


Michael Courtney

[Borachon]

Personally, I believe that within the next 25 years, we can see new designs that will make pistols as effective in incapacitating as the .223 is today.

Agreed. If not more so than a .223.

I'm not sure that the new designs will make it past the monolith of legality however. The more effective...and energy efficient...that you make a pistol; the more likely you'll see legislation to curtail it's development and use...for civilians at any rate.

Exploding bullets, rocket propelled bullets, armor piercing...all of these offer interesting concepts for bullet design. But they are often limited by regulation.

[Major Beer]

this might have been the most informative post i have read in ages. tomorrow is gun season here in Ohio - i will be using my 50 cal muzzleloader. after reading the report on the 40 S&W performance on a deer shooting, i know full well of its potential of a self defense cartridge.



who knows, i may try hand gunning for deer eventually. for now, i'll stick with something with a scope that i can easily drop Bambi's parents at 100 yards.

thank you for all your posts Mr. Courtney - - facinating indeed.

[Michael Courtney]

Agreed. If not more so than a .223.

I'm not sure that the new designs will make it past the monolith of legality however. The more effective...and energy efficient...that you make a pistol; the more likely you'll see legislation to curtail it's development and use...for civilians at any rate.

Exploding bullets, rocket propelled bullets, armor piercing...all of these offer interesting concepts for bullet design. But they are often limited by regulation.

The regulatory side is an RKBA/legal discussion. This discussion is very interesting and relevant, but being a scientist (rather than a lawyer or politician), I feel my greater potential for contribution is on the scientific side in seeking to describe cause and effect relationships (how to increase incapacitation).

Of course, one recognizes that there may be constraints imposed by legalities, so one also endeavors to discover the most effective possibilities within a given set of constraints. However, considering the possibilities without constraints is an important step to maximizing the potential within the constraints.

Michael Courtney

[Jeff White]

Göransson AM, Ingvar DH, Kutyna F: "Remote Cerebral Effects on EEG in High-Energy Missile Trauma". The Journal of Trauma. 28(1 Supplement):S204-S205; January 1988.

Suneson A, Hansson HA, Kjellström BT, Lycke E, and Seeman T: "Pressure Waves by High Energy Missile Impair Respiration of Cultured Dorsal Root Ganglion Cells". The Journal of Trauma. 30(4):484-488; 1990.

Suneson A, Hansson HA, Seeman T: "Pressure Wave Injuries to the Nervous System Caused by High Energy Missile Extremity Impact: Part II. Distant Effects on the Central Nervous System. A Light and Electron Microscopic Study on Pigs". The Journal of Trauma. 30(3):295-306; 1990.

Suneson A, Hansson HA, Seeman T: "Pressure Wave Injuries to the Nervous System Caused by High Energy Missile Extremity Impact: Part I. Local and Distant Effects on the Peripheral Nervous System. A Light and Electron Microscopic Study on Pigs". The Journal of Trauma. 30(3):281-294; 1990.

Suneson A, Hansson HA, Lycke E: "Pressure Wave Injuries to Rat Dorsal Cell Ganglion Root Cells in Culture Caused by High Energy Missiles". The Journal of Trauma. 29(1):10-18; 1989.

Suneson A, Hansson HA, Seeman T: "Central and Peripheral Nervous Damage Following High-Energy Missile Wounds in the Thigh". The Journal of Trauma. 28(1 Supplement):S197-S203; January 1988.

Suneson A, Hansson HA, Seeman T: "Peripheral High-Energy Missile Hits Cause Pressure Changes and Damage to the Nervous System: Experimental Studies on Pigs". The Journal of Trauma. 27(7):782-789; 1987.

How does your work differ from these works that have all been discredited?

Jeff

[Michael Courtney]

How does your work differ from these works that have all been discredited?


These works focus on wounding. Our focus is on incapacitation. Wounding is a secondary consideration.

Our primary emphasis is on predicting and observing incapacitation effects without being bound to the unpresupposition that easily detectable wounding is always necessary for rapid incapacitation.

We have observed these incapacitation effects directly, and also confirmed the Strasbourg Goat tests which implanted a pressure sensor and to detect the pressure wave in the carotid artery. The Strasbourg data shows a very strong correlation between average incapacitation time and the pressure wave magnitude.

Michael Courtney

[Jeff White]

Have you got a link to the Strasbourg tests?

Jeff

[ghost squire]

I think when when the FBI Wound Ballistics people (Fackler among them) looked at the Strasbourg goat tests, within minutes they concluded that they were false.

[Michael Courtney]

I think when when the FBI Wound Ballistics people (Fackler among them) looked at the Strasbourg goat tests, within minutes they concluded that they were false.

Yet to date, they are unable to provide conclusive evidence supporting this position.

The main case that the Strasbourg tests were fraudulent depends on their anonymity and the lack of supporting evidence (witnesses, documentation). However, reaching this conclusion "within minutes" based on anonymity and lack of supporting evidence is unsound.

In contrast, we have endeavored to test the hypothesis of fraud by using the results of the Strasbourg results of incapacitation times to make testable predictions of incapacitation in whitetail deer. Predictions based on Strasbourg are sufficiently accurate that this experiment has concluded with 90% certainty that the Strasbourg results represent genuine average incapacitation times.

In other words, if the Strasbourg tests were really fraudulent, they would show no correlation with a similar study in deer using substantially similar shot placement. The fact that the Strasbourg results can be used to accurately predict the results of a future experiment speak very strongly and directly to their validity.

Michael Courtney

[ghost squire]

Allright, that seems fair, do you think you could link me to a full copy of these tests so I can see for myself what you are talking about?

[james481]

Hmm, well, this is an interesting read, raising some interesting questions. If the TC is, in fact, just one of the observable effects of a larger "pressure wave", you feel that this pressure wave has positive effects on incapacitation times. Well, there is no doubt that a pressure wave of sufficient force can cause incapacitation through shock to the nervous system, but, AFAIK these types of pressure waves are usually not even produced by high velocity rifle rounds, usually only seen with the use of fast burning high explosives. So, my question is, if in fact the TC is just one effect of the overall "pressure wave", by what method does the "pressure wave" cause, or aid in, incapacitation? Is this a nervous system effect, or does this pressure wave lead to an increased rate of hemmorage, or something else?

James

[Michael Courtney]

Hmm, well, this is an interesting read, raising some interesting questions. If the TC is, in fact, just one of the observable effects of a larger "pressure wave", you feel that this pressure wave has positive effects on incapacitation times.


The TC is highly correlated with incapacitation time. It is less clear whether this indicates that the TC causes more rapid incapacitation, or merely that both the TC and rapid incapacitation are both caused by the pressure wave.


Well, there is no doubt that a pressure wave of sufficient force can cause incapacitation through shock to the nervous system, but, AFAIK these types of pressure waves are usually not even produced by high velocity rifle rounds, usually only seen with the use of fast burning high explosives.


Good point, but there should be some advantage to applying the wave internally.


So, my question is, if in fact the TC is just one effect of the overall "pressure wave", by what method does the "pressure wave" cause, or aid in, incapacitation?


Our research to date has concentrated on becoming more certain of the causal relationship than on the specific physiological mechanisms.

For example, it only makes sense to investigate the specific biological mechanisms by which a dangerous chemical causes cancer once it has been determined with a high degree of certainty that a causal relationship exists.

By analogy, we have delayed investigating specific physiological mechanisms until after we concluded with a high degree of certainty that the pressure wave is an important causal agent of incapacitation. We believe that experiments like the Strasbourg goat tests that concentrate on incapacitation are important in identifying incapacitation without regard to specific physiological mechanisms.


Is this a nervous system effect, or does this pressure wave lead to an increased rate of hemmorage, or something else?
James

Our ideas regarding specific physiological mechanisms are much less certain than our conclusion that the pressure wave can contribute significantly to incapacitation with handgun loads.

We tend to agree with the position put forward in:

Newgard, Ken, M.D.: "The Physiological Effects of Handgun Bullets: The Mechanisms of Wounding and Incapacitation." Wound Ballistics Review, 1(3): 12-17; 1992.

that incapacitaion from blood pressure drop due to internal bleeding will take around 5 seconds in a best-case scenario. We have also observed in deer that even the best shot placement with a 1.5" broadhead will take at least 5 seconds to produce incapacitation via blood-pressure drop. Therefore, we tend to believe that some effect other than bleeding is required to produce incapacitation in under 5 seconds.

However, using handgun loads that generate high pressure waves, we have observed instances of incapacitation in under 5 seconds without a direct hit to the CNS or supporting bone structure. Since we do not believe incapacitation this rapidly can be ascribed to bleeding, there must be another mechanism.

The Strasbourg observation using a pressure transducer in the carotid artery suggests the pressure wave impacting the brain may be important. We also believe that the blunt force trauma of the pressure wave on the spine may be able to cause temporary incapacitation to long enough for blood loss to take effect. We have observed cases where deer are shot with handgun bullets, drop immediately, and then regain mobility briefly until the loss of blood produces permanent incapacitation.

This leads us to consider the possibility that the pressure wave and blood loss work together in the more commonly observed immediate drop where the deer never regains mobility. In other words, the pressure wave produces temporary incapacitation for the 5-10 seconds needed for blood pressure drop to extend the incapacitation indefinitely.

In other observations, the deer doesn't become incapacitated for 2-3 seconds after bullet impact. Could the remote blunt force trauma on the spine or brain have this delayed effect? Could the incapacitation be resulting from a neurological effect shutting down some body systems?

We don't have definitive answers at this point, but we think we know what the questions are. Now that we have a high level of confidence that the pressure wave is an important causal agent in incapacitation, we are turning more attention toward considering specific physiological mechanisms.

Michael Courtney

[ghost squire]

However, using handgun loads that generate high pressure waves, we have observed instances of incapacitation in under 5 seconds without a direct hit to the CNS or supporting bone structure. Since we do not believe incapacitation this rapidly can be ascribed to bleeding, there must be another mechanism.

Emotional Fainting: An Involuntary Psycho-physiological Mechanism of Collapse

The unexplained magic of "energy transfer" is usually credited when a person immediately collapses unconscious after being shot in the torso with a handgun bullet. How else could someone be so quickly and decisively incapacitated, especially when the bullet didn't damage central nervous system organs, and the speed in which incapacitation took place precludes incapacitation by blood loss?

If you're a bullet company, you want people to believe that your product possesses unique powers to make bad guys instantly collapse. Energy transfer is popular belief, and you're going to tell your customers what they want to hear, despite the fact that there's no evidence whatsoever to support your claims or your customers' beliefs. If that's what the majority of your customers want to believe, then you're going to tell them that your bullets transfer more energy, and they do it faster and better than any other brand.

But if energy transfer isn't a mechanism of incapacitation, what is it that causes people to immediately collapse unconscious when other factors are ruled out?

In the last issue of Wound Ballistics Review, Fackler tackles this difficult question.¹ He identifies and describes a psycho-physiological mechanism of unconscious collapse called Emotional Fainting.

Fackler refers to Guyton2, and describes Emotional Fainting as "...[a] physiological mechanism, with an psychological cause, known as neurogenic shock — more specifically a type of neurogenic shock called 'Emotional Fainting'." Fackler explains:

"Strong emotions (such as fear) can cause widespread dilation of the body's blood vessels. These vessels have muscle fibers in their walls to allow them to constrict or dilate and thus vary blood flow as needed (in response to heat or cold, for example). The vessels are usually kept semi-constricted, but in Emotional Fainting, nerve impulses from the sympathetic nervous system can cause them to dilate completely. When this happens, the vascular capacity increases substantially and the blood available can no longer fill it. If the person is upright when this happens, gravity pulls the available blood into the legs and lower torso, starving the brain and causing the incapacitation."

Fackler continues:

"...the effects of Emotional Fainting, or some gradation of psychologically caused incapacitation (the gamut from surrender to Emotional Fainting), are either totally or partially responsible for much more of the observed reaction from bullet hits than is recognized. The practical result of this misinterpretation of the causes of reactions to being shot is overwhelming confounding effect on any attempt to compare efficacy of various bullets by observing, recording, and comparing the reactions of those hit."

Although Emotional Fainting appears to be a significant incapacitation mechanism, there's no evidence to suggest that any bullet characteristic (energy transfer, for example) triggers this reaction. While anecdotal reports of shootings seem to suggest that high-energy bullets are more effective in producing rapid incapacitation, these reports are tainted by the emotional bias of popular belief, which exaggerates stories that support the belief and suppresses those that do not.

Emotional Fainting is an unpredictable reaction and it is therefore unreliable. It is least likely to occur in people who are chemically intoxicated, psychotic, emotionally disturbed or acting with a single-minded determination to cause as much harm as possible before being stopped. It is probably most likely to occur in someone who is mentally unprepared to be shot or shot at.

Endnotes

Fackler, Martin L., M.D.: "Incapacitation Time." Wound Ballistics Review 4(1), Spring 1999; 4-8.

Guyton AC. Textbook of Medical Physiology, Eighth Ed., Philadelphia, PA. WB Saunders, 1992, p. 269.
http://www.firearmstactical.com/briefs29.htm

[RyanM]

Emotional Fainting: An Involuntary Psycho-physiological Mechanism of Collapse

It's a great article in the context in which it was written, but good luck getting a deer to emotionally faint.

[ghost squire]

Could it be the temporary cavity impacting the spine and knocking it unconcious? On a deer a broadside shot might let this happen fairly easily even with a handgun. On a human its unlikely because of all that stands between spine and chest, and the human is likely to be facing you.

[SDGlock23]

1350fps is about the max muzzle velocity attainable in the .40 and will be substantially higher than any reasonable impact velocity short of a contact wound...

I get a little over 1500 fps from my .40 (yes I reload), you're selling the .40 short bro.

[Michael Courtney]

It's a great article in the context in which it was written, but good luck getting a deer to emotionally faint.

The primary advantage of using deer is that we have a high level of certainty that observed incapacitation is involuntary and does not involve emotional fainting. In other words, it removes the "movie training" aspects of incapacitation that can be present in humans.

Michael Courtney

[Michael Courtney]

Could it be the temporary cavity impacting the spine and knocking it unconcious? On a deer a broadside shot might let this happen fairly easily even with a handgun. On a human its unlikely because of all that stands between spine and chest, and the human is likely to be facing you.

We don't think so, because in our handgun studies we carefully control shot placement very close to the horizontal midline. The TC only extends 2-3" from the wound channel, so that still leaves a significant gap between the highest point of the TC and the spine.

In observations with rifle bullets, we have also observed that there is a greater probability if immediate incapacitation in deer if the bullet hits 3" or so below the horizontal midline than if the bullet hits at the midline. This observation definitely suggests a pressure wave effect rather than the TC impacting the spine for two reasons:
1. This lower shot placement is closer to the aorta and more likely to transmit a large pressure wave to the brain.
2. Focussing effects in the ellipsoidal chest cavity produce a greater pressure wave at the spine with a hit lower in the chest than with a hit at the midline.

Michael Courtney

[lbmii]

The first thing we must do is to closely estimate the velocity that the 40 cal bullet was traveling when it hit the deer.

How sure are you of the distance?

Please chrono the round at that distance right away.

It is possible that the velocity was higher. But we need a test done to confirm.

I generally will go with a higher velocity bullet when choosing between two rounds of the same caliber and of about the same momentum. My carry round for my Glock 35 with a 5.3 inch barrel is the 155 grain gold-dot that I chronoed at 1245 fps.

But the first thing to do for this threads' discussion is to confirm the velocity of that 135 grain bullet. Please test for the velocity right away.

This is an excellent thread.

[Michael Courtney]

The first thing we must do is to closely estimate the velocity that the 40 cal bullet was traveling when it hit the deer.

How sure are you of the distance?

Please chrono the round at that distance right away.

It is possible that the velocity was higher. But we need a test done to confirm.

I generally will go with a higher velocity bullet when choosing between two rounds of the same caliber and of about the same momentum. My carry round for my Glock 35 with a 5.3 inch barrel is the 155 grain gold-dot that I chronoed at 1245 fps.

But the first thing to do for this threads' discussion is to confirm the velocity of that 135 grain bullet. Please test for the velocity right away.

This is an excellent thread.

We are in possession of the muzzleloading rifle used, as well as the identical lot of powder, bullet, sabot, and everything necessary to duplicate the load precisely. The location of the shooter was a permanent stand. The location of the deer was a pile of corn directly in front of a stack of firewood serving as a backstop. We will be able to measure the distance very accurately.

So, while the intitially reported distance is an estimate, we do intend to measure this exactly, as well as chronographing the load and measuring the time of flight to confirm the loss of velocity in flight. I prefer not to chronograph bullets at these ranges because uncertain accuracy can get expensive if the chronograph is hit. Using a time of flight measurement is standard in the industry for confirming ballistic coefficient.

We have permission to visit the privately owned site again soon to confirm everything necessary to be as certain as possible of the impact velocity.

Michael Courtney

[Michael Courtney]

The first thing we must do is to closely estimate the velocity that the 40 cal bullet was traveling when it hit the deer.

How sure are you of the distance?

Please chrono the round at that distance right away.

It is possible that the velocity was higher. But we need a test done to confirm.

I generally will go with a higher velocity bullet when choosing between two rounds of the same caliber and of about the same momentum. My carry round for my Glock 35 with a 5.3 inch barrel is the 155 grain gold-dot that I chronoed at 1245 fps.

But the first thing to do for this threads' discussion is to confirm the velocity of that 135 grain bullet. Please test for the velocity right away.

This is an excellent thread.

We were able to do some measurements at the original shooting site today. Our original estimate of the distance from gun to deer was 65 yards. The actual measured distance is 72 yards. Our original estimate of the impact velocity was 1350 FPS. Using a time of flight measurement of the bullet from the actual deer stand to the point where the deer was standing 72 yards away, our new estimate of the impact velocity is 1250 FPS. Some uncertainty remains (the impact velocity could have been slightly higher) since our measurements this morning were made at an ambient temperature of 18 degrees F, and the original shooting took place at an ambient temperature of 33 degrees F.

However, it is extremely unlikely that a temperature difference of 15 degrees F could cause an impact velocity increase over 100 ft/s. If we decide to include this result in a publication, we will arrange to perform our time of flight and chronograph measurements at closer to 33 degrees F.

Michael Courtney

[lbmii]

Interesting, by any chance did you get photos of the deer?

I now keep a disposable camera in my glove box just for those Kodak moments.

Did the bullet impact a rib or did it go between the ribs?

I once worked at a deer check in station and the wounds were somewhat greater when the bullet had struck a bone.

[Michael Courtney]

Interesting, by any chance did you get photos of the deer?

I now keep a disposable camera in my glove box just for those Kodak moments.


Yes, we've got photographs. They were posted to a Glocktalk thread of similar title. I am willing to post them here, but was concerned that the moderators may not approve.


Did the bullet impact a rib or did it go between the ribs?


We don't believe it is possible to determine with objective certainty whether or not a bullet has impacted a rib when entering a ruminant animal from the side. Post-mortem examination can only infer whether or not ribs are fractured and what kind(s) of fractures were sustained, but we do not believe that every bullet that hits a rib results in clear evidence of a fracture, nor do we believe that every fracture gives evidence of a rib hit.

Low velocity projectiles can sometimes glance off of a rib without creating a fracture. Bullets which create very large pressure waves can sometimes break ribs without impacting them directly. (We've observed cases with as many as three adjacent broken ribs with high pressure wave bullets, the bullet did not hit all three.)

In this case, the ribs were not fractured by the bullet on entrance. Given the bullet velocity, this probably means the bullet did not hit the ribs, but we would not conclude that with certainty.


I once worked at a deer check in station and the wounds were somewhat greater when the bullet had struck a bone.

This effect is more pronounced when the bullet hits hip, leg, or spine bones than with ribs. There are actually different schools of thought on whether hitting a rib is beneficial or detrimental to bullet performance. On the one hand, I think whether or not hitting a rib is beneficial depends on the bullet design and the velocity. On the other hand, I don't think the question can be reliably answered, because of the afore-mentioned difficulties in being certain whether or not a bullet hit a rib.

The Strasbourg Goat Tests attempted to address this question, but I think they lacked a truly objective criteria for determining whether or not a rib had been hit. I regard the Strasbourg Tests as an accurate measurement of incapacitation times, because their criteria for incapacitation was objective. However, I do not regard the Strasbourg Tests as a valid indicator of the benefit/detriment of hitting a rib, because they lacked an objective criteria for determining whether or not a rib had been hit.

Michael Courtney