Dr. Amy Courtney assisted me in re-writing the Hydrostatic Shock article on Wikipedia. We believe it is now much improved, with a more complete discussion and more complete reference list.

See:

en.wikipedia.org/wiki/Hydrostatic_shock

Thanks,

Michael Courtney

Interesting.



How does pressure damage the cells/tissue? Burst the cell wall?

Quoted: Interesting. How does pressure damage the cells/tissue? Burst the cell wall?

Yep.

Nice article.

Interesting.  I suggest posting in the ammunition forums.

For example, an 8 gram projectile at 360 m/s impacting a NIJ level II vest over the sternum can produce an estimated pressure wave level of nearly 2.0 MPa (200 PSI) in the heart and a pressure wave level of nearly 1.5 MPa (150 PSI) in the lungs. Impacting over the liver can also produce an estimated pressure wave level of 2.0 MPa (200 PSI) in the liver.

I still dont see how this is enough to cause damage to cells. Boxers/kick boxers apply this much pressure if not more from a kick/punch.......


What am I missing?

Quoted: For example, an 8 gram projectile at 360 m/s impacting a NIJ level II vest over the sternum can produce an estimated pressure wave level of nearly 2.0 MPa (200 PSI) in the heart and a pressure wave level of nearly 1.5 MPa (150 PSI) in the lungs. Impacting over the liver can also produce an estimated pressure wave level of 2.0 MPa (200 PSI) in the liver. I still dont see how this is enough to cause damage to cells. Boxers/kick boxers apply this much pressure if not more from a kick/punch....... What am I missing?

The speed possibly?

In that case, the velocity of the bullet does not have much to do with the amount of pressure exerted (as far as I know).  I'm not sure how much pressure is exerted onto the organ itself by a punch but I know that the average fighter with gloves can hit around 500-700psi, but heavyweights and such can hit much harder, probably closer to the high thousands.

Quoted: In that case, the velocity of the bullet does not have much to do with the amount of pressure exerted (as far as I know).  I'm not sure how much pressure is exerted onto the organ itself by a punch but I know that the average fighter with gloves can hit around 500-700psi, but heavyweights and such can hit much harder, probably closer to the high thousands.

Energy = mass * velocity ^ 2


Velocity, being squared, is a significant way to modify the energy being delivered.  So yes, velocity matters.

Interesting article, well sourced and nicely put together.  Good work!

Quoted: Quoted: In that case, the velocity of the bullet does not have much to do with the amount of pressure exerted (as far as I know).  I'm not sure how much pressure is exerted onto the organ itself by a punch but I know that the average fighter with gloves can hit around 500-700psi, but heavyweights and such can hit much harder, probably closer to the high thousands. Energy = mass * velocity ^ 2 Velocity, being squared, is a significant way to modify the energy being delivered.  So yes, velocity matters.

But energy is still the same thing. The equation you gave us is just showing us how energy is quantified.


Energy (total) from a a very heavy object moving slowly, and a light object moving very fast is the same. Energy doesnt changes, but the way in which it is transfered can.  




I guess speed may have something to do with it, but i imagine if I punched someone in the leg, you could measure a pressure spike in the brain just because of the media that humans are made out of.  

Quoted: Quoted: Quoted: In that case, the velocity of the bullet does not have much to do with the amount of pressure exerted (as far as I know).  I'm not sure how much pressure is exerted onto the organ itself by a punch but I know that the average fighter with gloves can hit around 500-700psi, but heavyweights and such can hit much harder, probably closer to the high thousands. Energy = mass * velocity ^ 2 Velocity, being squared, is a significant way to modify the energy being delivered.  So yes, velocity matters. But energy is still the same thing. The equation you gave us is just showing us how energy is quantified. Energy (total) from a a very heavy object moving slowly, and a light object moving very fast is the same. Energy doesnt changes, but the way in which it is transfered can.

I am only making the point regarding the relevance of velocity when it comes to energy transfer.  Read the first sentence in the post I replied to.

What I intended to imply in the first sentence was what Hoody has said, my mistake.

I'm thinking that the surface are of the impact zone would also affect how energy was transfered into the target medium(human body)

that is, a lot of force concentrated into a smaller area (bullet impact) would transfer energy differently than more energy over a greater surface are (boxer's punch) i.e. PSI

any thoughts or opinions to this?

Quoted: For example, an 8 gram projectile at 360 m/s impacting a NIJ level II vest over the sternum can produce an estimated pressure wave level of nearly 2.0 MPa (200 PSI) in the heart and a pressure wave level of nearly 1.5 MPa (150 PSI) in the lungs. Impacting over the liver can also produce an estimated pressure wave level of 2.0 MPa (200 PSI) in the liver. I still dont see how this is enough to cause damage to cells. Boxers/kick boxers apply this much pressure if not more from a kick/punch....... What am I missing?

2 things:

Geometry. The contact area of a boxing glove is ~4"x5". That's 20 square inches. The max static force a boxer that benches 400 lbs can exert is 200 lbs. That results in 10 psi on the skin. That's a very simplified version since we are leaving out dynamics but it's ballpark and shows you the importance of factoring in the area when trying to determine pressure. Remember you can lift a jumbo jet with only a few PSI of pressure differential because the huge area of the wings.

Physiology. As even Fackler will say, the temporary cavity stretch in gelatin can correspond to permanent damage in some tissue, depending on the tissue. ie brain matter and liver tissue cannot absorb much energy before being permanently damaged, not much pressure/stretch is required here.

Ooh, I gotta tag this for later.

Quoted: Quoted: For example, an 8 gram projectile at 360 m/s impacting a NIJ level II vest over the sternum can produce an estimated pressure wave level of nearly 2.0 MPa (200 PSI) in the heart and a pressure wave level of nearly 1.5 MPa (150 PSI) in the lungs. Impacting over the liver can also produce an estimated pressure wave level of 2.0 MPa (200 PSI) in the liver. I still dont see how this is enough to cause damage to cells. Boxers/kick boxers apply this much pressure if not more from a kick/punch....... What am I missing? 2 things: Geometry. The contact area of a boxing glove is ~4"x5". That's 20 square inches. The max static force a boxer that benches 400 lbs can exert is 200 lbs. That results in 10 psi on the skin. That's a very simplified version since we are leaving out dynamics but it's ballpark and shows you the importance of factoring in the area when trying to determine pressure. Remember you can lift a jumbo jet with only a few PSI of pressure differential because the huge area of the wings. Physiology. As even Fackler will say, the temporary cavity stretch in gelatin can correspond to permanent damage in some tissue, depending on the tissue. ie brain matter and liver tissue cannot absorb much energy before being permanently damaged, not much pressure/stretch is required here.

I understand the glove area, but when a boxer hits someones gut and applies and a  force is applied, it is not limited to 200 lbs (in your example). That is the force the boxer can push with, but when striking it can be much greater. Think of jumping on a scale, even though you never weigh more then whatever your weight is.  


I have been trying to visualize a boxers punch and a bullet impact, and there is no way the bullet comes anywhere close to hitting as hard as a boxer can. I dont know how many ft-lbs of energy a boxers punch has, but I can imagine that trying to catch a boxers puch in your hands would be MUCH harder then handling the rocoil of a fire arm; I mean in terms of force.


If a bullet hitting a vest can impart a 200 PSI pressure wave to the liver, the pressure wave from a boxers punch must be much greater, and we dont see any cell damage like this associated with boxers. <---My guess

Physiology. As even Fackler will say, the temporary cavity stretch in gelatin can correspond to permanent damage in some tissue, depending on the tissue. ie brain matter and liver tissue cannot absorb much energy before being permanently damaged, not much pressure/stretch is required here.

I would be willing to bet that this damage is from streching and not pressure; at least in muscle tissue that is. Look at gel tests filmed in slow motion. They undergo a tremendous amount of streching.


However, on the opposite argument, i cant get past tests like Old_Painless does with his box of truth, where the pressure of the water jugs being shot literally blows the sides of the box out.

The average force exerted by the bullet is its energy in ft-lbs divided bythe path length (if it comes to a stop) or the energy loss (energy in minus energy out) divided by the path length.
This force is exerted over a very small area.

Even moderate forces over small areas can produce a rather high PSI.

A .30 cal bullet has a cross section of only 0.074 in^2.
If you push with only 10 pounds on the base of the bullet you will create a pressure of 134 PSI.

Scale the ten pounds up to the average force the bullet is exerting as it dissipates its energy of hundreds (handguns) to thousands (long guns) of ft-lbs in the target.

A 2000 ft-lb projectile that travels 10 inches has exerted an average force of 2400 lb.
Divided by the area and you are looking at ~32,000 PSI.
It IS going to penetrate and do a b~3273unch of damage on the way.

The actual numbers will be affected by the fact that the slowing of the bullet is NOT uniformly linear, and the effective area is increased by the deformation of the elastic target and some bullet expansion.
Think how much force is required to deform a bullet and remember something else received the same force as the bullet expanded.

The numbers are still pretty large though, with a typically higher rate of energy loss initially than straight line declining to a lower rate of energy loss quickly.

Recoil is a much lower energy activity since we have traded weight for speed in the momentum conservation.
An 8 pound rifle weighs ~373 times more than a 150 grain bullet.
The velocity is thus 1/373 of the bullet, and since energy is 0.5 * m * v^2 the energy is MUCH lower.
The area of the but of a rifle is also measured in multiple square inches.

height=8

Quoted: 2 things: Geometry. The contact area of a boxing glove is ~4"x5". That's 20 square inches. The max static force a boxer that benches 400 lbs can exert is 200 lbs. That results in 10 psi on the skin. That's a very simplified version since we are leaving out dynamics but it's ballpark and shows you the importance of factoring in the area when trying to determine pressure. Remember you can lift a jumbo jet with only a few PSI of pressure differential because the huge area of the wings.

I'm willing to bet that's most of it right there. I mean think about how a bulletproof vest works. The bullet still can break ribs and bruise you but the reason it doesn't penetrate and kill is because all of the energy is displaced from that relatively small bullet tip to a much larger surface area. It's still the exact same amount of energy behind the bullet.

Very interesting. Thanks.

Man, I'm glad you math and science guys know what you are doing.  I just want the projectile to kill the target...

Quoted: Interesting. How does pressure damage the cells/tissue? Burst the cell wall?

Mammals don't have cell walls.  The cell membranes can be burst close to the wound channel where the pressure waves are very high, but in the regions further away, most damage occurs from the motion of one cell relative to another.  

Keep in mind that the nervous system operates by the transmission of electrical signals from one neuron to another, and this transmission can be disrupted by relative motion between the cells and minor damage to the cell membranes without actually bursting the cell membrane.

Michael Courtney

Quoted: Quoted: Interesting. How does pressure damage the cells/tissue? Burst the cell wall? Mammals don't have cell walls.  The cell membranes can be burst close to the wound channel where the pressure waves are very high, but in the regions further away, most damage occurs from the motion of one cell relative to another.   Keep in mind that the nervous system operates by the transmission of electrical signals from one neuron to another, and this transmission can be disrupted by relative motion between the cells and minor damage to the cell membranes without actually bursting the cell membrane. Michael Courtney

I knew that, I really did.



Interesting, the rest of it actually makes intuitive sense. So obviously the pressure wave is much more a factor for nervous tissue, and really only affects the other cells when they are close to the wound channel. Neat, and thanks for your reply.



I am curious how this compares with a boxers punch/kick. When a fighter is hit in the head there must be a big pressure wave. Is the mechanism the same for this and a projectile impact pressure wave you have observed? I understand that many fighters have lasting neurological disorders and was wondering if this is why.....

HAHA...complex issue no doubt.

Thank you for posting that update.  

Country Boy Ballistics:


1.Pistol bullets make holes

2. Big Pistol Bullets make Bigger Holes

3. Rifles Tear &#^!  UP

Quoted: Interesting, the rest of it actually makes intuitive sense. So obviously the pressure wave is much more a factor for nervous tissue, and really only affects the other cells when they are close to the wound channel. Neat, and thanks for your reply. I am curious how this compares with a boxers punch/kick. When a fighter is hit in the head there must be a big pressure wave. Is the mechanism the same for this and a projectile impact pressure wave you have observed? I understand that many fighters have lasting neurological disorders and was wondering if this is why.....

The main mechanisms are very different.  A penetrating projectile creates a pressure wave that radiates outward from the projectile through the viscoelastic materials.

When a boxer's punch hits someone in the head, any pressure wave that might be imparted directly by the fist is stopped by the skull.  Any brain injury results from the acceleration of the head.  If the head acceleration is large enough, the brain itself can be injured by rattling around inside of the skull.  Rotational accelerations can also cause injury via the stresses on the brain stem because the brain initially resists the rotational motion.  Interestingly enough, the stresses and pressures associated with this kind of brain injury have be computed and are comparable in magnitude with ballistic pressure wave magnitudes shown to cause brain injury.

Michael Courtney

So when are your studies of the ballistic wave in small animals in water and in deer shooting going to be published in peer-reviewed journals? When is the data on which these studies are based going to be available for review?  

Quoted: So when are your studies of the ballistic wave in small animals in water and in deer shooting going to be published in peer-reviewed journals? When is the data on which these studies are based going to be available for review?

I am not sure if these are what you are talking about, but there are several articles on google scholar. I just googled Michael Courtney +pressure wave and got several. They are in PDF format.

Quoted: Quoted: Quoted: For example, an 8 gram projectile at 360 m/s impacting a NIJ level II vest over the sternum can produce an estimated pressure wave level of nearly 2.0 MPa (200 PSI) in the heart and a pressure wave level of nearly 1.5 MPa (150 PSI) in the lungs. Impacting over the liver can also produce an estimated pressure wave level of 2.0 MPa (200 PSI) in the liver. I still dont see how this is enough to cause damage to cells. Boxers/kick boxers apply this much pressure if not more from a kick/punch....... What am I missing? 2 things: Geometry. The contact area of a boxing glove is ~4"x5". That's 20 square inches. The max static force a boxer that benches 400 lbs can exert is 200 lbs. That results in 10 psi on the skin. That's a very simplified version since we are leaving out dynamics but it's ballpark and shows you the importance of factoring in the area when trying to determine pressure. Remember you can lift a jumbo jet with only a few PSI of pressure differential because the huge area of the wings. Physiology. As even Fackler will say, the temporary cavity stretch in gelatin can correspond to permanent damage in some tissue, depending on the tissue. ie brain matter and liver tissue cannot absorb much energy before being permanently damaged, not much pressure/stretch is required here. I understand the glove area, but when a boxer hits someones gut and applies and a  force is applied, it is not limited to 200 lbs (in your example). That is the force the boxer can push with, but when striking it can be much greater. Think of jumping on a scale, even though you never weigh more then whatever your weight is.   I have been trying to visualize a boxers punch and a bullet impact, and there is no way the bullet comes anywhere close to hitting as hard as a boxer can. I dont know how many ft-lbs of energy a boxers punch has, but I can imagine that trying to catch a boxers puch in your hands would be MUCH harder then handling the rocoil of a fire arm; I mean in terms of force. If a bullet hitting a vest can impart a 200 PSI pressure wave to the liver, the pressure wave from a boxers punch must be much greater, and we dont see any cell damage like this associated with boxers. <---My guess Physiology. As even Fackler will say, the temporary cavity stretch in gelatin can correspond to permanent damage in some tissue, depending on the tissue. ie brain matter and liver tissue cannot absorb much energy before being permanently damaged, not much pressure/stretch is required here. I would be willing to bet that this damage is from streching and not pressure; at least in muscle tissue that is. Look at gel tests filmed in slow motion. They undergo a tremendous amount of streching. However, on the opposite argument, i cant get past tests like Old_Painless does with his box of truth, where the pressure of the water jugs being shot literally blows the sides of the box out.

But we do see cell damage from boxing.
It appears as bruising and swelling, and an occasional cut (often from being forced against bony structures).
Kidney punches are not allowed as unsportsmanlike, but blood in the urine from tissue damage is a common result from striking the back near the kidneys.

There are MANY affects on the CNS that are very difficult to diagnose.
Multiple sclerosis produces VERY localized swelling within the CNS that is the major cause of the external symptoms.
Swelling within the spinal column of the cord following trauma (or things like MS activity) can easily create enough pressure on the nerves to impair normal function.
There is NO macroscopic rise in CNS pressure that can be measured however.

Quoted: But we do see cell damage from boxing. It appears as bruising and swelling, and an occasional cut (often from being forced against bony structures). Kidney punches are not allowed as unsportsmanlike, but blood in the urine from tissue damage is a common result from striking the back near the kidneys. There are MANY affects on the CNS that are very difficult to diagnose. Multiple sclerosis produces VERY localized swelling within the CNS that is the major cause of the external symptoms. Swelling within the spinal column of the cord following trauma (or things like MS activity) can easily create enough pressure on the nerves to impair normal function. There is NO macroscopic rise in CNS pressure that can be measured however.

Thats a good point,.,,

Quoted: Quoted: So when are your studies of the ballistic wave in small animals in water and in deer shooting going to be published in peer-reviewed journals? When is the data on which these studies are based going to be available for review?   I am not sure if these are what you are talking about, but there are several articles on google scholar. I just googled Michael Courtney +pressure wave and got several. They are in PDF format.

The PDFs to which you refer are ArXiv papers. ArXiv is not peer reviewed.

They also do not contain substantial information. For example, in the one on the effects of shooting deer, there is ONE table that compares two different rounds. Dr. Courtney has stated in the past that he has shot hundreds of deer using lots of different calibers. The paper list data for only ten deer, all shot with just two different loadings. Looking at the table, each of the two tested rounds had an outlier. If we remove the outliers, the average results of the two rounds gets much closer. In fact, the difference is no longer statistically significant, even at the 25% level, let alone at the typical 5% level. In other words, his entire paper rest on two statistically aberrant data points.

The deer study he describes would likely not pass muster in a peer reviewed journal. There are too many issues. I even discussed this with Dr. Courtney in the ammunition forum here over 2-1/2 years ago. Just to mention a few that come to mind: The paper talks about how the average weight of the deer in the two samples differed only a little. However, it does not tell us about what if any correlation there may be between actual weight and distance to incapacitation. In other words, the deer that traveled 0 yards may have been the smallest, while the one that ran 162 yards may have been the largest. Remember, these two outliers are SOLELY responsible for the statistically signficant effect that Dr. Courtney found. How was the 1" above and below the centerline of the deer measured prior to the shooting of each animal? If this was determined AFTER the deer was alread dead, how many samples were discarded for this cause, and what was their distribution as to which round was used and distance to incapacitation. What if any, analysis was done on the vertical displacement from the centerline and the time to incapacitation? He posits an average running speed of a wounded deer as 10 yards/second without any attribution of where this number comes from. Since his whole theory is that TIME to incapacitation is a function of the magnitude of the ballistic pressure wave, why not directly measure the TIME to incapacitation, rather than distance, which may or may not be a good analog? He admits in the paper that the velocity of pistol bullets shot from muzzleloaders can be highly variable, but fails to disclose the ACTUAL velocity of each shot in the test (which should be available given his acoustical recording methods). Again, since the magnitude of the ballistic pressure wave is at least partially a function of impact velocity, it is of central importance to know more precisely what those velocities were.

I do not wish for you or anyone to conclude that I am accusing Dr. Courtney of dishonesty. Dr. Courtney has admitted on here that the study was not blinded, let alone double blinded. There is a very good reason that medical studies are double blinded. Since it appears that animals were removed from the study sample (the paper talks about removing those found in poor health and those that varied too much from the ideal hit location) AFTER knowing both which round was used and the distance the animal travelled... Well, I think he found what he hoped to find.

BTW, I teach experimental design as part of my job. I have seen with my own eyes people finding effects they were looking for when using poorly designed experiments. These same effects could not be replicated in a well designed experiment, something the original testers all found profoundly baffling. In not one of these cases did I suspect willful fraud. Just the natural human desire to get the result you were hoping for. After all, there really is no deception like self deception.

Quoted: The PDFs to which you refer are ArXiv papers. ArXiv is not peer reviewed. They also do not contain substantial information. For example, in the one on the effects of shooting deer, there is ONE table that compares two different rounds. Dr. Courtney has stated in the past that he has shot hundreds of deer using lots of different calibers. The paper list data for only ten deer, all shot with just two different loadings. Looking at the table, each of the two tested rounds had an outlier. If we remove the outliers, the average results of the two rounds gets much closer. In fact, the difference is no longer statistically significant, even at the 25% level, let alone at the typical 5% level. In other words, his entire paper rest on two statistically aberrant data points. The deer study he describes would likely not pass muster in a peer reviewed journal. There are too many issues. I even discussed this with Dr. Courtney in the ammunition forum here over 2-1/2 years ago. Just to mention a few that come to mind: The paper talks about how the average weight of the deer in the two samples differed only a little. However, it does not tell us about what if any correlation there may be between actual weight and distance to incapacitation. In other words, the deer that traveled 0 yards may have been the smallest, while the one that ran 162 yards may have been the largest. Remember, these two outliers are SOLELY responsible for the statistically signficant effect that Dr. Courtney found. How was the 1" above and below the centerline of the deer measured prior to the shooting of each animal? If this was determined AFTER the deer was alread dead, how many samples were discarded for this cause, and what was their distribution as to which round was used and distance to incapacitation. What if any, analysis was done on the vertical displacement from the centerline and the time to incapacitation? He posits an average running speed of a wounded deer as 10 yards/second without any attribution of where this number comes from. Since his whole theory is that TIME to incapacitation is a function of the magnitude of the ballistic pressure wave, why not directly measure the TIME to incapacitation, rather than distance, which may or may not be a good analog? He admits in the paper that the velocity of pistol bullets shot from muzzleloaders can be highly variable, but fails to disclose the ACTUAL velocity of each shot in the test (which should be available given his acoustical recording methods). Again, since the magnitude of the ballistic pressure wave is at least partially a function of impact velocity, it is of central importance to know more precisely what those velocities were. I do not wish for you or anyone to conclude that I am accusing Dr. Courtney of dishonesty. Dr. Courtney has admitted on here that the study was not blinded, let alone double blinded. There is a very good reason that medical studies are double blinded. Since it appears that animals were removed from the study sample (the paper talks about removing those found in poor health and those that varied too much from the ideal hit location) AFTER knowing both which round was used and the distance the animal travelled... Well, I think he found what he hoped to find. BTW, I teach experimental design as part of my job. I have seen with my own eyes people finding effects they were looking for when using poorly designed experiments. These same effects could not be replicated in a well designed experiment, something the original testers all found profoundly baffling. In not one of these cases did I suspect willful fraud. Just the natural human desire to get the result you were hoping for. After all, there really is no deception like self deception.

Seem like pretty good observations, I will have to read them (I didnt read them, just found them) and see what I think.


Thanks for your input

Quoted: The PDFs to which you refer are ArXiv papers. ArXiv is not peer reviewed.

In fairness, you should also mention that many oft-cited works in wound ballistics were not published in peer-reviewed journals.  Examples include:

ML Fackler, What's Wrong with the Wound Ballistics Literature and Why
U Patrick, Handgun Wounding Facors and Effectiveness

Quoted: Dr. Courtney has admitted on here that the study was not blinded, let alone double blinded. There is a very good reason that medical studies are double blinded.

Blinding of studies in ballistics is problematic because in many cases, different firearms are used and it is unrealistic for the shooter to be ignorant of the firearm being used, and in every case, it would be a violation of gun safety rules for the shooter not to have personally observed the loading of the firearm.  

It is disengenuous to suggest that using a firearm loaded by another person is widely used in any area of ballistics.  I have read hundreds of peer-reviewed journal articles in ballistics, and none of them employed blinding, including ones published in medical journals.  For example, Fackler, Wang, Suneson, and many other groups publish peer-reviewed live animal testing in wound ballistics without blinding.

Quoted: If we remove the outliers, the average results of the two rounds gets much closer.

There is no justification for removing any points.  Arbitrarily removing points from a data set that meet the selelection criteria is not sound science.  

"It is unethical to ignore outlying values in statistical analyses or to avoid reporting them."  -- TA Lang, M Secic, How to Report Statistics in Medicine.

Quoted: AFTER knowing both which round was used and the distance the animal travelled... Well, I think he found what he hoped to find.

No animals were removed for poor health.  All the cases that were removed for sub-optimal shot placement were cases of significant deviations (6" or more) out of the intended impact zone.  There simply nothing subjective about whether or not cases were removed that might have benefitted from blinding.  In addition, the performance (average distance) of the two loads would be even further apart if the removed cases had been included.

Quoted: BTW, I teach experimental design as part of my job. I have seen with my own eyes people finding effects they were looking for when using poorly designed experiments. These same effects could not be replicated in a well designed experiment, something the original testers all found profoundly baffling.

Yet the results of our deer experiment are in good agreement with other experiments.

Every published data set that allows for comparison of relative incapacitation measures for loads with different pressure waves supports the pressure wave hypothesis.  The suggestion of remote neural effects is supported with many peer reviewed papers.   So while the deer experiment itself, in isolation, is not a slam dunk irrefutable proof of hydrostatic shock, it is in agreement with a broad base of peer-reviewed resutls.  

In addition to the deer experiment, the wikipedia article cites supporting evidence from 20 or so peer-reviewed scientific journals.  In contrast, the most commonly cited refutations (HWFE and What's Wrong) were neither peer-reviewed, nor do they cite published data to support their assertions.  

The peer-reviewers of our paper "Links between traumatic brain injury and ballistic pressure waves . . ." accepted that there is considerable evidence in the literature and published data.  

Michael Courtney

Well Dr. Courtney, can you please post information on what statistical test you performed to determine that the two rounds delivered statistically different results. I performed:

2-sample T
ANOVA
Mann-Whitney
Mood's Median (due to the presence of outliers)

None of these were significant at the 5% level. And that is leaving in all 10 data points.

As for removing outliers (which you claim should not be done), your article states that your removed samples for "poor health" and shots that were placed improperly. Without blinding the study so that the person making he decision to remove the samples did NOT know which round was used, you open yourself to the charge that bias was present in the removal of samples. You cannot have your cake and eat it too.

Quoted: Well Dr. Courtney, can you please post information on what statistical test you performed to determine that the two rounds delivered statistically different results. I performed: 2-sample T ANOVA Mann-Whitney Mood's Median (due to the presence of outliers) None of these were significant at the 5% level. And that is leaving in all 10 data points. As for removing outliers (which you claim should not be done), your article states that your removed samples for "poor health" and shots that were placed improperly. Without blinding the study so that the person making he decision to remove the samples did NOT know which round was used, you open yourself to the charge that bias was present in the removal of samples. You cannot have your cake and eat it too.

You are quibbling about one out of three lines of reasoning in the deer paper that supports the reality of hydrostatic shock.  The deer paper represents one out of 26 papers cited as scientific evidence for hydrostatic shock.  The 26 papers cited in support for hydrostatic shock represent the view of 41 well-qualified scientists and medical doctors.  How significant is the lack of a 95% confidence level in one of 26 papers?

As stated previously, since the two mean drop distances are further apart than their estimated uncertainties (the error bars do not overlap), it can be said that the high pressure wave load has a significantly smaller drop distance than the low pressure wave load.  Non-overlapping error bars is a standard method to conclude that two means are significantly different.  Recall that the low pressure wave load produced a mean drop distance of roughly 100 yards and the high pressure wave load produced a mean drop distance of roughly 50 yards.  The uncertainties in the mean were roughly 15 yards, so the conclusion that the means are different is well-supported.    

You are right that the level of confidence is less than 95% by most statistical tests.  However, supposing that your favorite statistical test only yields an 80% confidence level (that one mean is significantly smaller than the other), does this mean that the results are irrelevant?

Is only an 80% confidence level in one of three lines of reasoning insignificant in light of the fact that the paper also reports increased wounding potential of higher pressure wave bullets?

The article does not say that animals were removed due to poor health, only that the experimental design call for removal if animals were determined to be in poor health.   No animals were removed due to poor health.  In addition, the significant differences in wounding between low and high pressure wave bullets make it impossible to insure that those conducting a necropsy are ignorant of (blinded to) which bullet was used.  

As discussed in the paper, low pressure wave bullets wound mainly by crush and create a wound channel roughly 0.7” in diameter with almost no wounding easily observable beyond this diameter.  In contrast, high pressure wave bullets create both a much larger wound channel as well as significant tissue damage and hemorrhaging that is easily observable well beyond the wound channel.  In light of this, it is unrealistic to think that a necropsy team could be effectively blinded to whether any given animal was hit by a low or a high pressure wave bullet.  This would be obvious to anyone reading the paper with sufficient care to be qualified to offer criticism.  

It would also be obvious to anyone familiar with the wound ballistics literature that blinding is not used in wound ballistics research.  Can you cite a single published wound ballistics study where blinding was used?  Perhaps you can get a letter published in J Trauma complaining that the wound ballistics studies of Fackler et al., Suneson et al., Goransson et al., and Wang et al. should have been blinded.  Do you think they will rejoice that you have caught an important error missed by their editors and peer-reviewers?  Should all the published findings of Fackler, MacPherson, Roberts, Wolberg, and everyone else be ignored because they did not conduct blind studies?

You are so keen on removing “outliers” that one wonders how many papers you have published utilizing this technique.  I can point to a number of papers I have published in peer-reviewed journals where no outliers were removed from the data.  Perhaps you will be kind enough to point to a few of your own peer-reviewed publications utilizing your technique of removing outliers.

The bottom line is that the deer paper supports the idea of hydrostatic shock with three distinct lines of reasoning.  Even if one of the lines of support only has an 80% confidence level, the paper supports the reality of hydrostatic shock at handgun energy levels.  

Or would you argue that “hydrostatic shock” is a myth after all if one of 26 cited papers only has an 80% confidence level in support for the pressure wave hypothesis?

Michael Courtney

I have neither the mathematics, the scientific or medical background to go toe to toe with either side of this issue or even to determine which side is correct by reading the works of both sides.

Because of the above I consider hydrostatic shock kind of like icing on the cake.  I don't rely on it, but if it happens I'll take it and be thankful.  The cake being direct crush damage and a permanent wound cavity.

But I sure enjoy the discussions as long as it stays civil.

Mr Courtney,

I would be interested in knowing which calibers/loads you found to be most effective at producing hydrostatic shock.  Is that published somewhere?  Thanks.

Interesting.

The general formula for estimating pressure wave magnitudes of JHP pistol bullets is

p = 5E/(pi d),

where p is the peak pressure wave (in PSI), E is the impact energy (in ft-lbs), and d is the penetration depth in gelatin (in feet).  At any given level of penetration, more energy is a good thing.

Some of our papers (references in the Hydrostatic Shock article) have tables in the back for a number of loads.  The guys at GlockTalk have applied this formula to a number of loads.

From: http://glocktalk.com/forums/showthread.php?t=827375

Here's the info on Double Tap and Winchester ammo. KE = kinetic energy in foot-pounds, P = penetration depth in inches, E = expanded bullet diameter in inches, psi = peak ballistic pressure wave in pounds to the square inch, and ci = cubic inches of wound volume for the whole penetration depth listed, not accounting for any damage outside the direct bullet path, if any exists. Velocities are shown in feet/second. All penetration depths are based on clothed gel. Win 380auto T Series, 95gr, 1000fps, KE=211, P=7.95, E=.64, 2.6ci, 507psi DT 9mm+P Gold Dot, 115gr, 1415fps, KE=511, P=12.00, E=.70, 4.6ci, 813psi DT 9mm+P Gold Dot, 124gr, 1310fps, KE=472, P=13.25, E=.70, 5.1ci, 684psi Win9mm+P T Series, 124gr, 1180fps, KE=383, P=13.90, E=.67, 4.9ci, 526psi Win 9mm+P Bonded, 124gr, 1180fps, KE=383, P=18.70, E=.54, 4.3ci, 392psi Win9mm+P+TSeries, 127gr, 1250fps, KE=441, P=12.20, E=.68, 4.4ci, 691psi DT 9mm+P Gold Dot, 147gr, 1125fps, KE=413, P=14.00, E=.66, 4.8ci, 563psi Win 9mm T Series,,,,, 147gr, 990fps, KE=320, P=14.50, E=.66, 5.0ci, 422psi Win 9mm Bonded,,,,,, 147gr, 995fps, KE=323, P=16.50, E=.59, 4.5ci, 374psi DT 357SIG Gold Dot, 115gr, 1550fps, KE=613, P=12.25, E=.71, 4.9ci, 955psi DT 357SIG Gold Dot, 125gr, 1450fps, KE=584, P=14.50, E=.66, 5.0ci, 770psi Win357SIG T Series, 125gr, 1350fps, KE=506, P=12.10, E=.66, 4.1ci, 798psi Win357SIG Bonded,, 125gr, 1350fps, KE=506, P=15.90, E=.57, 4.1ci, 608psi DT 357SIG Gold Dot, 147gr, 1250fps, KE=510, P=14.75, E=.73, 6.2ci, 661psi DT 357mag Gold Dot, 125gr, 1600fps, KE=710, P=12.75, E=.69, 4.8ci, 1063psi DT 357mag Gold Dot, 158gr, 1400fps, KE=688, P=19.00, E=.56, 4.7ci, 692psi DT 9X25 Gold Dot, 115gr, 1800fps, KE=827, P=10.00, E=.64, 3.2ci, 1579psi DT 9X25 Gold Dot, 125gr, 1725fps, KE=826, P=15.00, E=.74, 6.5ci, 1051psi DT 9X25 Gold Dot, 147gr, 1550fps, KE=784, P=17.50, E=.68, 6.4ci, 856psi DT 40S&W Nosler,,,, 135gr, 1375fps, KE=567, P=12.10, E=.72, 4.9ci, 894psi DT 40S&W Gold Dot, 155gr, 1275fps, KE=559, P=13.00, E=.76, 5.9ci, 825psi DT 40S&W Gold Dot, 165gr, 1200fps, KE=528, P=14.00, E=.70, 5.4ci, 721psi Win40S&W T Series, 165gr, 1140fps, KE=476, P=13.20, E=.70, 5.1ci, 690psi Win 40S&W Bonded, 165gr, 1140fps, KE=476, P=19.00, E=.55, 4.5ci, 479psi DT 40S&W Gold Dot, 180gr, 1100fps, KE=484, P=14.75, E=.68, 5.4ci, 626psi Win40S&W T Series, 180gr,, 990fps, KE=392, P=14.30, E=.70, 5.5ci, 524psi Win 40S&W Bonded, 180gr, 1070fps, KE=458, P=21.80, E=.51, 4.5ci, 402psi DT 10mm Nosler,,,, 135gr, 1600fps, KE=767, P=11.00, E=.70, 4.2ci, 1332psi DT 10mm Gold Dot, 155gr, 1475fps, KE=749, P=13.50, E=.88, 8.2ci, 1061psi DT 10mm G. Saber, 165gr, 1425fps, KE=744, P=14.75, E=.82, 7.8ci, 964psi DT 10mm Gold Dot, 165gr, 1400fps, KE=718, P=14.25, E=1.02, 11.6ci, 962psi DT 10mm Gold Dot, 180gr, 1300fps, KE=675, P=15.25, E=.96, 11.0ci, 846psi DT 10mm G. Saber, 180gr, 1330fps, KE=707, P=16.00, E=.85, 9.1ci, 844psi DT 10mm Hor. XTP, 180gr, 1350fps, KE=728, P=17.25, E=.77, 8.0ci, 808psi DT 10mm Hor. XTP, 200gr, 1250fps, KE=694, P=19.50, E=.72, 8.0ci, 680psi Win 45GAP T Series, 230gr, 905fps, KE=418, P=12.70, E=.72, 5.2ci, 630psi DT 45auto Gold Dot, 185gr, 1225fps, KE=616, P=12.75, E=.82, 6.7ci, 923psi DT 45auto Gold Dot, 200gr, 1125fps, KE=562, P=14.25, E=.88, 8.7ci, 753psi DT 45auto Gold Dot, 230gr, 1010fps, KE=521, P=15.25, E=.95, 10.8ci, 653psi Win 45auto T Series, 230gr, 905fps, KE=418, P=12.70, E=.72, 5.2ci, 630psi Win45auto+PTSeries, 230gr, 990fps, KE=500, P=15.20, E=.78, 7.3ci, 628psi Win 45 auto Bonded, 230gr, 905fps, KE=418, P=15.80, E=.67, 5.6ci, 506psi

http://arxiv.org/ftp/physics/papers/0701/0701267.pdf

I thought the Strasbourg tests were considered debunked?

X number of animals all weighing within 4lbs of one another, etc?

Quoted: http://arxiv.org/ftp/physics/papers/0701/0701267.pdf I thought the Strasbourg tests were considered debunked? X number of animals all weighing within 4lbs of one another, etc?

There were many, many logical fallacies in the purported "debunking."

A more complete review is available at:

http://arxiv.org/ftp/physics/papers/0701/0701268.pdf

In addition to many fallacies in the criticisms of Strasbourg, one also has the undeniable fact that many findings consistent with Strasbourg have been published.  How many "debunked" studies find an impressive level of agreement with other published data?

Michael Courtney

Bear with me, for I am a layman when it comes to this sort of thing.

But in my time treating injuries, the only ones I've seen that caused instant incapacitation were head wounds.

I've never noticed any concussion-type symptoms in GSW victims.

And I've seen people with GSWs in non-vital areas continue fighting.

A good example of this is the video of the guy who gets shot in the chest by a sniper, the round is stopped by his SAPI plate, he gets knocked down, then back up instantly and moves to cover.

If there was a "remote" effect, wouldn't that Soldier have some visible issues?

Quoted: Bear with me, for I am a layman when it comes to this sort of thing. But in my time treating injuries, the only ones I've seen that caused instant incapacitation were head wounds. I've never noticed any concussion-type symptoms in GSW victims. And I've seen people with GSWs in non-vital areas continue fighting. A good example of this is the video of the guy who gets shot in the chest by a sniper, the round is stopped by his SAPI plate, he gets knocked down, then back up instantly and moves to cover. If there was a "remote" effect, wouldn't that Soldier have some visible issues?

Remote effects are not 100% with handgun energy levels.  However, the Hydrostatic Shock article documents a number of cases of remote effects in both human case studies and live animal experiments.  If you treat gunshot wounds to the chest that generate > 1000 PSI, you will probably see some GCS numbers that indicate mild TBI (assuming, of course, surviving patients are being screened for concussion effects in the first few hours post injury).  

We haven't measured ballistic pressure waves behind an armor plate, but I doubt that they exceed the 1000 PSI threshold for easily observable effects.  Too much energy is absorbed by the plate.

Michael Courtney

A good example of this is the video of the guy who gets shot in the chest by a sniper, the round is stopped by his SAPI plate, he gets knocked down, then back up instantly and moves to cover.

Since we know the round that hit him does NOT have enough energy to actually knock him down we had better look into what other mechanisms could produce the clearly observed effect.
Make him stumble? Maybe.
If he was off balance tip him over? Maybe.
Actually knock him off his feet? No way.

Keep in mind that the momentum of the bullet cannot exceed the momentum of the rifle recoil.
This is NOT an energy process.

Quoted: A good example of this is the video of the guy who gets shot in the chest by a sniper, the round is stopped by his SAPI plate, he gets knocked down, then back up instantly and moves to cover. Since we know the round that hit him does NOT have enough energy to actually knock him down we had better look into what other mechanisms could produce the clearly observed effect. Make him stumble? Maybe. If he was off balance tip him over? Maybe. Actually knock him off his feet? No way. Keep in mind that the momentum of the bullet cannot exceed the momentum of the rifle recoil. This is NOT an energy process.

Physics aside, the video showed him standing, getting shot, getting knocked on his back.

Quoted: Quoted: Bear with me, for I am a layman when it comes to this sort of thing. But in my time treating injuries, the only ones I've seen that caused instant incapacitation were head wounds. I've never noticed any concussion-type symptoms in GSW victims. And I've seen people with GSWs in non-vital areas continue fighting. A good example of this is the video of the guy who gets shot in the chest by a sniper, the round is stopped by his SAPI plate, he gets knocked down, then back up instantly and moves to cover. If there was a "remote" effect, wouldn't that Soldier have some visible issues? Remote effects are not 100% with handgun energy levels.  However, the Hydrostatic Shock article documents a number of cases of remote effects in both human case studies and live animal experiments.  If you treat gunshot wounds to the chest that generate > 1000 PSI, you will probably see some GCS numbers that indicate mild TBI (assuming, of course, surviving patients are being screened for concussion effects in the first few hours post injury).   We haven't measured ballistic pressure waves behind an armor plate, but I doubt that they exceed the 1000 PSI threshold for easily observable effects.  Too much energy is absorbed by the plate. Michael Courtney

That was going to be my next question, is there an effect with handgun rounds and if so considering that rifle rounds can have 5-8 times as much energy as handgun rounds, why is the effect not correspondingly greater?

Would it only be to the chest? Or would extremities count?

For example I helped treat a Marine who was shot in the arm with 7.62x51 ball, his injury was pretty localized, I didn't have him recite numbers backwards but he was quite "with it" and didn't give off the concussion vibe that I would have picked up off an IED victim.

Physics aside, the video showed him standing, getting shot, getting knocked on his back.

It would seem that some other effect might be in play then?

Quoted: That was going to be my next question, is there an effect with handgun rounds and if so considering that rifle rounds can have 5-8 times as much energy as handgun rounds, why is the effect not correspondingly greater?

The important parameter is the peak ballistic pressure wave magnitude (BPW) rather than the impact energy or velocity.  JHP pistol loads can generate BPW magnitudes larger than FMJ rifle loads, because BPW is proportional to the local rate of energy transfer rather than impact energy.  

FMJ bullets which neither expand or fragment transfer energy relatively slowly until they tumble.  The depth and rate of energy transfer when an FMJ rifle bullet tumbles is highly variable.

Quoted: Would it only be to the chest? Or would extremities count?

Extermity hits are unlikely to cause remote BPW effects in humans because there is not a good path for the pressrure wave to reach the central nervous system.  A hit that transferred 2000 ft-lbs to the thigh could possibly have a wave reach the CNS via the femoral artery, but the distance the wave needs to travel is much larger than the distance involved with thoracic hits.  In addition, hits to the thoracic cavity give rise to much greater reflection effects than extremity hits.  

I cannot really say effects from extremity hits are impossible, just much less likely given the greater distances and more complicated transmission mechanisms.

Michael Courtney

Quoted: Quoted: That was going to be my next question, is there an effect with handgun rounds and if so considering that rifle rounds can have 5-8 times as much energy as handgun rounds, why is the effect not correspondingly greater? The important parameter is the peak ballistic pressure wave magnitude (BPW) rather than the impact energy or velocity.  JHP pistol loads can generate BPW magnitudes larger than FMJ rifle loads, because BPW is proportional to the local rate of energy transfer rather than impact energy.   FMJ bullets which neither expand or fragment transfer energy relatively slowly until they tumble.  The depth and rate of energy transfer when an FMJ rifle bullet tumbles is highly variable. Quoted: Would it only be to the chest? Or would extremities count? Extermity hits are unlikely to cause remote BPW effects in humans because there is not a good path for the pressrure wave to reach the central nervous system.  A hit that transferred 2000 ft-lbs to the thigh could possibly have a wave reach the CNS via the femoral artery, but the distance the wave needs to travel is much larger than the distance involved with thoracic hits.  In addition, hits to the thoracic cavity give rise to much greater reflection effects than extremity hits.   I cannot really say effects from extremity hits are impossible, just much less likely given the greater distances and more complicated transmission mechanisms. Michael Courtney

So if I am understanding you correctly, shot placement and bullet construction continue to be the two most important factors when it comes to self defense?

Quoted: So if I am understanding you correctly, shot placement and bullet construction continue to be the two most important factors when it comes to self defense?

Bullet construction doesn't help much if the energy just isn't there.

The important considerations are shot placement, energy transfer, and penetration.

Bullet construction should assure both adaquate energy tranfer and penetration, but it is impossible to transfer more energy than the bullet has.  

Michael Courtney

Bullet placement is most important and don't let all of this energy/shock/construction distract from that one important fact!!!

You can have a bullet constructed from unobtainium and enough energy to achieve orbit, but if you shoot a deer through the ear or a people through the hand – you got nothing!

A mere lead ball from a 36 cap and ball blackpowder revolver through the heart will put them down every time…

Quoted: Quoted: So if I am understanding you correctly, shot placement and bullet construction continue to be the two most important factors when it comes to self defense? Bullet construction doesn't help much if the energy just isn't there. The important considerations are shot placement, energy transfer, and penetration. Bullet construction should assure both adaquate energy tranfer and penetration, but it is impossible to transfer more energy than the bullet has.   Michael Courtney

Sorry for the delay in responding, I've been on the road.

Is there truly a difference between a 400lb/ft handgun load and a 600lb/ft handgun load when it comes to personal defense?

If so, does the difference justify the reduced (penetration) performance of the higher energy load?

For example, the lower energy 147gr vs the higher energy 357 Sig.