why isnt two holes better than one?

[Shifty]

some of you guys are still confusing hydraulic effect with "hydrostatic shock"

outside of the temporary cavity created by very high velocity rounds, the pressure exerted upon the bodies vascular system is significantly less than the stress created from a regular heartbeat. LOL with me here people, it will not reverse bloodflow, starve or overfill the brain or organs, or cause them to magically shutdown from a pressure shock. that is what hydrostatic shock theory was believed to be. an attempt to explain why sometimes, game animals (and people) sometimes just dropped in their tracks after being shot.

there is the neurological shock/impact theory (different from, but similar to psychologic shock). a massive shock to the nervous system by powerful extensive nerve damage outside of the actual CNS itself, not directly a head or spine shot.....but at what point does it cause permanent versus temporary incapacitation, and how variable is it. (body size, muscle density, mental state, etc) as far as i know, it has not been accurately measured, (imagine trying to get approval for that study) proven or disproven.

 

[Riktoven]

My personal opinion is that the pressure wave effect is capable of tissue damage. I don't believe most man-portable weapons inflict damage through this mechanism however.

I think the main factor here is psychological. The pressure wave is real, and moves faster through liquids and solids than air. I don't think it's at all unreasonable to suspect that those pressure waves rippling at high speed past hundreds of thousands of nerve cells around the POI could cause a 'pain overload' to the victim, essentialy causing them to faint.

That would also explain the limited effectiveness of all small arms in Somalia, what with that narcotic plant they chew on. It might also explain why .357 mag rounds tend to be more effective than a .38 with the same bullet (assuming expansion, and wound path to be identical).

Just a personal opinon, based on limited information and no real world experience.

On a side note, I have seen two separate Rotweillers shot by police on two separate occasions. Actually I've seen mroe than two, but these two stick out. Both dogs were shot in the head, one with 9mm, one with a .45. Both bullets bounced off thier skulls and both dogs ran like hell to be euthanised when they were later caught. Proof that there are no guarantees in life.

 

[Archangel]

I have no idea what your training is, nor what your field of specialty.

Since you and Michael have both shared information about yourselves, it's probably only fair that I do the same.

While my career has gone off in another direction, I have a Bachelor's degree in Biochemistry. So I know a little about scientific method and experimental controls, etc, though certainly not as much as Michael Courtney.

I also minored in Electronic & Computer Music, where I learned quite a bit about waves and wave physics. Again, Michael's PhD level knowledge of wave physics will trump what I know.

I'll also admit that I've never actually shot anything living, nor cut up anything recently living (other than a dissection or two long enough ago that they can't count for anything). I have seen some bullet wound autopsy photos, not that that counts for much compared to seeng them in person.

I have tried to make up for a lack of firsthand experience with wound ballistics by reading as much as I can about it from (hopefully) reliable sources. That reading has so far been pretty Fackleriffic, but I am working on finding some other viewpoints to read. (I've tracked down a couple of the papers Michael cited, but have not had a chance to read them yet.)

 

[Archangel]

Should I therefore dismiss this anecdotal observation because of the meteorologists training and equipment? Would you?

I'm not suggesting that scientists and their equipment is never wrong, nor am I suggesting that you should not believe what you have seen with your own eyes. But, if a deer were do drop dead in front of you, would you be able to diagnose that it had died from Coronary Artery Disease?

A surgeon studies anatomy from the perspective of trying to keep the body alive, as opposed to harvesting food. The point I was trying to make was that perhaps it's possible that someone with a surgeon's level of anatomical knowledge would notice something that you would not know to look for or be able to recognize, that could lead to a different interpretation of the same observations.

 

[Archangel]

So, I got to thinking last night. Which can be dangerous, I know.

Anyway, it occurred to be that we may not be disagreeing as much as we think. What I realized was that I was thinking about temperary cavity the wrong way. Even though I had used the phrase "tissue displaced by temperary cavitation," I was only thinking about the cavity itself.

Say we have a theoretical .5 inch bullet, which leaves a .5 inch diameter permanent cavity and a 2.5 inch diameter temperary cavity. That means that tissue is propelled out 1 inch sideways from the edge of the permanent cavity. So, is 1.25" from the center of the permanent cavity the limit of tissue affected by temporary cavitation?

No. That 1 inch of tissue that is pushed out sideways doesn't just compress away into nothing, it compresses into the tissue behind it. If we assume that the tissue is compressible to a ratio of 2:1 (entirely theoritcal, Michael could probably give us a better idea how much real tissue can be compressed) then the 1 inch of tissue from right next to the wound channel is compressed down to 1/2", and the inch from behind it is compressed as well. But that second inch will only compress down to something like 3/4", because it compresses the inch behind it down to 7/8", which compresses the inch behind it to 15/16", etc. Or something like that.

Like I said, the numbers are all theoretical, but the process is, I think, pretty much what actually happens. So you could have tissue that is "displaced by temporary cavitation" several inches outside of the actual cavity. And if some of that tissue is an organ like the liver, which is less elastic than the surrounding tissue, then you could have an organ, away from the actual wound track, that is damaged by temporary cavitation.

Here's the rub. The process I just described, under the auspices of temporary cavity, is also the beginning of a compression wave. Like when a speaker cone moves and compresses the air in front of it, and the compression moves through the air across the room in the form of a sound wave. The compression radiating out from the wound will also continue on through the surrounding tissue.

So, really, I think a lot of what we're arguing is just semantics. I am, and have been for a while, completely convinced that a pressure wave does propogate out from the site of the wound. I'm still reserving judgement as to how much wounding potential it has distant to the wound. Since a wave will lose energy over distance, logic would follow that if it didn't have the energy to damage tissue right at the wound, it can't have it farther away. Except for the less-flexible organ situation described above.

I suppose it's theoretically possible that you could get a point of constructive wave interference that could cause tissue damage distant from the wound.

I don't know. I think I started rambling a couple paragraphs ago. Michael, does any of this make sense, or am I just babbling incoherently?

 

[Michael Courtney]

outside of the temporary cavity created by very high velocity rounds, the pressure exerted upon the bodies vascular system is significantly less than the stress created from a regular heartbeat.

Wrong, wrong, wrong. It is a simple matter to put a high-speed pressure gauge into a living test subject or ballistic gelatin to confirm that the pressure wave magnitude beyond the temporary cavity can be orders of magnitude greater than normal blood pressure. Suneson et al. measured the ballistic pressure wave magnitude to be as large as 30 PSI as far as 18" from the bullet impact. At the edge of a 3" diameter temporary cavity, the ballistic pressure wave from a handgun bullet can be over 100 PSI. So your assertion that "the pressure exerted upon the bodies vascular system is significantly less than the stress created from a regular heartbeat" is simply false.

LOL with me here people, it will not reverse bloodflow, starve or overfill the brain or organs, or cause them to magically shutdown from a pressure shock.

It's not magic. Some of the articles to which I referred above (the ones dealing with the fluid percussion model of tramautic brain injury) have shows conclusively that pressure waves in the 15-30 PSI range can cause immediate incapacitation and neurological injury.

Michael Courtney

 

[Michael Courtney]

Here's the rub. The process I just described, under the auspices of temporary cavity, is also the beginning of a compression wave. Like when a speaker cone moves and compresses the air in front of it, and the compression moves through the air across the room in the form of a sound wave. The compression radiating out from the wound will also continue on through the surrounding tissue.

So, really, I think a lot of what we're arguing is just semantics. I am, and have been for a while, completely convinced that a pressure wave does propogate out from the site of the wound. I'm still reserving judgement as to how much wounding potential it has distant to the wound. Since a wave will lose energy over distance, logic would follow that if it didn't have the energy to damage tissue right at the wound, it can't have it farther away. Except for the less-flexible organ situation described above.

In addition to the less flexible organ situation, there are two other important factors contributing to remote pressure wave effects:

1. Once a wave is confined to a tube, it loses very little amplitude over distance. Consider a blast pressure wave confined to a cave, a light wave confined to a optical fiber, or a sound wave propagating through an empty garden hose. If the tube narrows, the wave can even gain intensity.

2. There is the possibility for the pressure wave being focussed. Some of our observed pressure wave wounding in deer was at the location where a pressure wave originating at the center of the chest would be focussed after reflecting from the rear of the thoracic cavity. Think about a sound wave being focused by a parabolic microphone, a radio wave being focussed by a satellite dish, or light waves being focussed by a concave mirror.

I suppose it's theoretically possible that you could get a point of constructive wave interference that could cause tissue damage distant from the wound.

Yes, this can happen also.


Michael Courtney

 

[Meplat]

I'm not suggesting that scientists and their equipment is never wrong, nor am I suggesting that you should not believe what you have seen with your own eyes. But, if a deer were do drop dead in front of you, would you be able to diagnose that it had died from Coronary Artery Disease?

Given the amount of study I've done over the past six years (the subject has become somewhat close to my heart - pardon the weak pun), I'd say that I could NOT conclusively state that the deer in question had died from a myocardial infarction. What I COULD tell you was if the animal had CAD. I've enough curiosity, and seen enough actual hearts with clogged ateries (the University Medical Centers I've been attended to at are more than willing to do anything within their means to help you make wise life choices - and especially the rehab departments. This goes up to and includes "scaring you right" if you show the requisite curiostity.) They have allowed me to examine hearts that were preserved for study. And, I could tell you to a pretty high degree of certainty whether any necrosis of the heart muscle had occured due to past infarct, and whether the muscle was enlarged or the non-necrotic areas flaccid due to overwork from taking up the slack from the damaged portions. I have viewed my own heart both via ultra-sound and while lying on a table watching the monitor while being cathed too often to not recognize necrosis in a heart muscle or the attendant enlargement, flaccidness of the overworked remaining healthy tissue, etc. I would have to be totally honest with you here, though, and tell you no - I could not state unequivacally that the deer had died of infarction or whether it had a cerbral or pulmonary clot thown due to a portion of the plaque breaking off, or some other cause altogether. CAD in and of itself doesn't kill, it is rather a mechanism that leads to death. Very subtle hair splitting, but that seems to be the order of this whole excercise. CAD is the mechanism by which other fatal events are triggered. IOW, it causes things like stroke from high blood pressure, congestive heart failure, thrown clots, or necrosis by starving the heart muscle of blood and oxygen. I could reasonably believe that CAD had contributed to one of these (or many other) conditions given no other obvious causual effects, but no, I could not conclusively state that fact.

A surgeon studies anatomy from the perspective of trying to keep the body alive, as opposed to harvesting food. The point I was trying to make was that perhaps it's possible that someone with a surgeon's level of anatomical knowledge would notice something that you would not know to look for or be able to recognize, that could lead to a different interpretation of the same observations.

Quite possibly. Scratch that, most highly probable. HOWEVER, to date all I have seen in this partcular debate is references to studies that state that things I have personally witnessed don't occur. This is what I find unacceptable. In the above mentioned case of the deer, I would reasonably believe that the animal had indeed died of a coronary related event. I certainly would discount anything that said deer don't have coronary disease if I had seen proof to the contrary with my own eyes. If someone told me that something other than CAD had caused the animal's demise and could show that conclusively, I certainly would not argue that point. I would however, catagorically dismiss anyone who told me the deer had no indications of coronary disease if I could see it for myself, which is what Facklers studies are saying re: bullet perfomance in living tissue.

 

[Meplat]

So, I got to thinking last night. Which can be dangerous, I know.

I sometimes do that myself, and find myself on the same dangerous limb.

Anyway, it occurred to be that we may not be disagreeing as much as we think.

From what you have stated below, we just may have some semantical differences at that.

What I realized was that I was thinking about temperary cavity the wrong way. Even though I had used the phrase "tissue displaced by temperary cavitation," I was only thinking about the cavity itself.

And I was more concerned with the damaged tissue that was definitely irreprable surrounding the actual path of the bullet. Any irreprable damage done to muscle and organs has to have some impact on a bullet's killing abilities.

Say we have a theoretical .5 inch bullet, which leaves a .5 inch diameter permanent cavity and a 2.5 inch diameter temperary cavity. That means that tissue is propelled out 1 inch sideways from the edge of the permanent cavity. So, is 1.25" from the center of the permanent cavity the limit of tissue affected by temporary cavitation?

No. That 1 inch of tissue that is pushed out sideways doesn't just compress away into nothing, it compresses into the tissue behind it. If we assume that the tissue is compressible to a ratio of 2:1 (entirely theoritcal, Michael could probably give us a better idea how much real tissue can be compressed) then the 1 inch of tissue from right next to the wound channel is compressed down to 1/2", and the inch from behind it is compressed as well. But that second inch will only compress down to something like 3/4", because it compresses the inch behind it down to 7/8", which compresses the inch behind it to 15/16", etc. Or something like that.

I can't argue about the mechanics of that theory at all, AA. It's one I could accept as a possible explaination of things I had actually seen, and certainly couldn't dismiss it. Once again, I'd like to see some scientific studies done in this area. Then again, Mr. Courtney has already hinted at some European and Asian studies that may do just that.

Like I said, the numbers are all theoretical, but the process is, I think, pretty much what actually happens. So you could have tissue that is "displaced by temporary cavitation" several inches outside of the actual cavity. And if some of that tissue is an organ like the liver, which is less elastic than the surrounding tissue, then you could have an organ, away from the actual wound track, that is damaged by temporary cavitation.

Actually, I believe that if you took into account even the fairly low velocity of a .357 or .44 mag round (compared to the much higher velocities of rifle rounds), it would account for MUCH tissue damage outside of the path of the bullet. I do know that having once been on the recieving end of a plastic blowgun round intended to sting dogs out of the garbage without doing them any permanent damage, that bruising, and therefore tissue damage from this VERY low velocity projectile radiated for several inches around the point of impact, which, BTW did not penetrate the skin. (It also produced some bruising effects on my idiot cousin who fired it, but that is another thread altogether.) This projectile was plastic, weighed only a few grains, and was of very low velocity as stated above. It was roughly .45-.50 caliber range, so I can only imagine how much more surrounding tissue would have been damaged had it's weight gone up to, say 240 grains, and it's velocity increased to vicinity of 1400 fps.

Here's the rub. The process I just described, under the auspices of temporary cavity, is also the beginning of a compression wave. Like when a speaker cone moves and compresses the air in front of it, and the compression moves through the air across the room in the form of a sound wave. The compression radiating out from the wound will also continue on through the surrounding tissue.

So, really, I think a lot of what we're arguing is just semantics. I am, and have been for a while, completely convinced that a pressure wave does propogate out from the site of the wound. I'm still reserving judgement as to how much wounding potential it has distant to the wound. Since a wave will lose energy over distance, logic would follow that if it didn't have the energy to damage tissue right at the wound, it can't have it farther away. Except for the less-flexible organ situation described above.

Actually, what you have hypothesized doesn't sound that far fetched to me, and I would go one step further and say that I would believe that it could account for damage even to more elastic muscle tissue. Of course, unless we can talk Dr. Fackler into using some of his grant monies, or better yet, send us a check and a few truckloads of equipment, we are going to have a hard time proving it. I'm not saying I am hopping on this bandwagon, but it does at least address things that I have personally witnessed.

I suppose it's theoretically possible that you could get a point of constructive wave interference that could cause tissue damage distant from the wound.

I am by no means wed to the theory of hydrostatic shock. As I said in an earlier post, if someone could show me why it was an invalid theory, and do so without telling me what I had seen happen hadn't happened, I'd be more than willing to admit that the theory was wrong. I just have honestly not seen any of the works up to this point that meet both those criteria.

I don't know. I think I started rambling a couple paragraphs ago. Michael, does any of this make sense, or am I just babbling incoherently?

I too, am most eager to hear Mr. Courtney's take on this. Perhaps his studies can support it, perhaps not. Either way, I'd respect his opinion on what to me seems a valid, logical look at this as something that might be causing this particular phenomenon to occur.

 

[Michael Courtney]

I too, am most eager to hear Mr. Courtney's take on this. Perhaps his studies can support it, perhaps not. Either way, I'd respect his opinion on what to me seems a valid, logical look at this as something that might be causing this particular phenomenon to occur.

The compression mechanism described above is one wave that the ballistic pressure wave is created and propagates through tissue. However, since we prefer to define the ballistic pressure wave as the force per square inch that would be measured by a high speed pressure sensor, we should mention that the compression mechanism is not a complete picture.

We have a pretty good idea what a ballistic pressure wave liiks like from high-speed pressure transducer measurements. We also have a good idea how to accurately estimate the peak pressure wave magnitude from colelge Physics (see the post "_The Physics of the Ballistic Pressure Wave_". We have also succeeded in correlating these peak pressure wave estimates to quantitative measures of incapacitation.

Detailed analysis of the time and frequency analysis and relative magnitudes of different contributing mechanisms is a much more complicated undertaking. It's not that it cannot be done, or should not be done, but it the more complex analysis makes it much harder to communicate the essential elements of the process to folks without a degree in Mechanical Engineering or Physics.

In most areas of science, it is sufficient to define a quantity by the method used to measure that quantity (a high speed pressure transducer, in this case) without needing to describe all the details about the causal mechanisms.

Michael Courtney

 

[Shifty]

Wrong, wrong, wrong. It is a simple matter to put a high-speed pressure gauge into a living test subject or ballistic gelatin to confirm that the pressure wave magnitude beyond the temporary cavity can be orders of magnitude greater than normal blood pressure. Suneson et al. measured the ballistic pressure wave magnitude to be as large as 30 PSI as far as 18" from the bullet impact. At the edge of a 3" diameter temporary cavity, the ballistic pressure wave from a handgun bullet can be over 100 PSI. So your assertion that "the pressure exerted upon the bodies vascular system is significantly less than the stress created from a regular heartbeat" is simply false.



It's not magic. Some of the articles to which I referred above (the ones dealing with the fluid percussion model of tramautic brain injury) have shows conclusively that pressure waves in the 15-30 PSI range can cause immediate incapacitation and neurological injury.

Michael Courtney

ok, balistic gelatin and water are not people. pressure waves dont travel through people uniformly and you know that. i have not fully read the studies you cited but i do not doubt the science behind them. but i do fully believe that if you blasted 1500torr back up some poor bastages carotid that he would pop something.

having said that, its nonsense to assume an impact creating 3 dimensional pressure wave will single out a vessel and pump all its amplitude directly up it. it will propagate outwards, weakening as it encounters resistance, and damaging the weakest areas first. it will not manifest as a perfect pressure wave up the major vessels. if you fired a bullet right into the axis of a major artery perhaps.... otherwise the elasticity of the vasular system combined with the variable density of the body will dissapate the pressure. before it can cause more than localized damage. localized can still mean a large area if the velocity of the bullet is high enough. (railgun anyone)

i have seen localized aneurysms and organ contusions from bullet impacts immediately adjacent to entrance wounds, but never on the magnitude that you are alluding to. how many transient traumatic ashpyxiations or intercranial hemorrhages have you seen from thorasic or abdominal gunshot wounds??

if what you say is true, then everytime someone gets socked in the gut they risk "hydrostatic shock"???!!!11!

i personally have much more faith in the nerve damage/overload and incapacite theory, and its spotty at best.

sorry, drinking and arguementative, your salvo........

 

[Michael Courtney]

ok, balistic gelatin and water are not people. pressure waves dont travel through people uniformly and you know that.

The ballistic pressure wave has been measured in live animal testing, as well as in ballistic gelatin and water. There is substantial quantitative agreement between ballistic gelatin and live animal measurements of the ballistic pressure wave.

i have not fully read the studies you cited but i do not doubt the science behind them. but i do fully believe that if you blasted 1500torr back up some poor bastages carotid that he would pop something.

having said that, its nonsense to assume an impact creating 3 dimensional pressure wave will single out a vessel and pump all its amplitude directly up it. it will propagate outwards, weakening as it encounters resistance, and damaging the weakest areas first. it will not manifest as a perfect pressure wave up the major vessels. if you fired a bullet right into the axis of a major artery perhaps.... otherwise the elasticity of the vasular system combined with the variable density of the body will dissapate the pressure. before it can cause more than localized damage. localized can still mean a large area if the velocity of the bullet is high enough. (railgun anyone)

A ballistic pressure wave created by a handgun bullet can have a magnitude over 1000 PSI at the edge of a 1" diameter cylinder centered on the axis of the bullet path. Only 15-30 PSI needs to reach the brain to create incapacitation. You are right that the magnitude of the pressure wave decreases with distance, but it seems clear that there are cases where enough of the pressure reaches the CNS to cause incapacitation.

i have seen localized aneurysms and organ contusions from bullet impacts immediately adjacent to entrance wounds, but never on the magnitude that you are alluding to. how many transient traumatic ashpyxiations or intercranial hemorrhages have you seen from thorasic or abdominal gunshot wounds??

Check out the references, there does not need to be an intercranial hemorrhage to cause incapacitation or traumatic brain injury.

if what you say is true, then everytime someone gets socked in the gut they risk "hydrostatic shock"???!!!11!

A steeringwheel to the chest at 60 MPH can create a pressure wave comparable to some pistol bullets, but a punch in the stomach is much smaller.

i personally have much more faith in the nerve damage/overload and incapacite theory, and its spotty at best.

I have no evidence against this mechanism, but the evidence supporting it is much thinner.

Michael Courtney