Hydrostatic shock

[mavracer]

What you describe could also be termed Hydraulic, or Hydrodynamic shock. If the pressure wave damages tissue, it is not hydrostatic. Maybe that is where people get confused.

No actually most people are confused because they really don't understand the subject, some even go so far as to try to argue semantics incorrectly.

Originally Posted by Merriam Webster

of or relating to fluids at rest or to the pressures they exert or transmit

The pressure wave transmitted through tissue is hydrostatic.
Temporary cavity would be the hydrodynamic part

Ft-lbs of energy does NOT equate directly to Hydrostatic shock.

It's much closer related to kinetic energy than it is directly to velocity.

Hydrostatic shock only comes into play at velocities above some number, which is arguable. 2100 to 2300 fps is the range most ballistics experts agree that it occurs above.

If it required 2000 fps there would never be internal injuries in car accidents

[Double Naught Spy]

"...Native Americans, killing bison..." Usually by running 'em off a cliff. Using a bow or spear to kill a buff is incredibly dangerous. Native's couldn't risk losing the people who defended the villages. Arrows were used, primarily, to lay claim to a carcass by an individual. Said arrow having personal markings on it.

As an archaeologist who has analyzed faunal remains from a few bison kill sites and human camp sites with bison remains, I can tell you for a fact that most bison were NOT killed by running the off cliffs. In Texas alone, there are hundreds of bison sites where there are no cliffs to be had. Kansas and Oklahoma have a lot as well. People were killing bison all over the place. If bison were around, people were killing them for food and raw material, no cliffs required.

The 1000 ft/lbs number is a manufactured number sold to hunters as the minimum to reliably kill game animals. Oooookaay . . . so answer me this, how did the settlers 300 years ago almost exterminate deer, elk, moose, antelope, grizzly bears, etc?

You can kill a lot of animals with underpowered ammo and poorly placed shots. They may not die right away, but they often die. 1000 ft/lbs seems to have been a marketing scheme for more ethical hunting to keep hunters from using less adequate means and shoot game and then fail to recover it.

What you describe could also be termed Hydraulic, or Hydrodynamic shock. If the pressure wave damages tissue, it is not hydrostatic. Maybe that is where people get confused.

No actually most people are confused because they really don't understand the subject, some even go so far as to try to argue semantics incorrectly.

Maybe somebody could provide the definitional and operational parameters of the terms being used so that the rest of us could understand the differences clearly? What are the correct semantics and what are the sources/bases for saying so?

[.50cal packer]

Let me introduce a new question, into this equation... How is it a whitetail, Mule or black tail deer, can be hit in the vital areas and run. Where as snipers in the military can shoot and when the bullet hits the target, they fall instantly? A deer weighing less than a human runs, not knowing a bullet is coming, going through both lungs or a heart. Yet an enemy soldier, in the heat of battle, falls down on contact. "Most of the time." I know there are lots of stories of people being shot multiple times and they just kept fighting. But is it Hydrostatic shock that keep them down, and how does that not apply to game animals?

[mavracer]

How is it a whitetail, Mule or black tail deer, can be hit in the vital areas and run.

They don't always. I've seen quite a few deer "bang flop" from heart lung shot. Just like most all critters including humans hydrostatic shock is a joker in the equation. Dr Courtney's reserch is excellent on the subject and show pretty clearly it can happen at ~500 ft lbs but by the same tokon it's not guaranteed at 2000 ft lbs, although it's far more likely.

[.50cal packer]

They don't always. I've seen quite a few deer "bang flop" from heart lung shot.

Ok. I won't state every deer will/can run. I've yet to see it. Doesn't by any means, say it can't happen. What deer I've seen "bang flop," has been from shoulder shots. Slow motion film shows a good array of waves travel, before they fall over. I'm still guessing the shot took both lungs and bone, leaving the animal incapable of moving.

[Boogershooter]

I can't answer your question but I've read alot of articles on this subject. First off most snipers shoot for center at targets facing them. It just so happens the spine is in the center of humans.

The difference with humans is the fact that alot of the civilian shootings occur with people that are on drugs. When we realize we have been shot our brain does funny things. But once it is deprived of oxygen it won't matter. Game animals have no idea what just happened to them. They instinctively run from any fear. Their brain doesn't tell them OMG I've been shot I'm gona die. They don't lay down, they run. I've never seen them watching TV shows that give them the impression if they are shot they are gona die.

The spine on game animals is a smaller target than the heart lung area. Alot of us think our deer rifles and our shooting abilities are as accurate as snipers and their rifles but that is for the most part not true. We shoot for the highest percentage of a lethal hit.

Most civilians are shot with pistols and not rifles. That alone makes a huge difference. In my life I've known 9 people that were shot by a rifle and only one lived. I know atleast that many people who have been shot by a pistol and still walking around today. I myself was shot by a 32 auto when I was 8 years old. It barely went under the skin on the inside of my elbow at 50 yards.

My brother, my cousin and myself heard some shooting thru the woods. We cut thru the woods thinking it was our dad's shooting on the back 40. It was a neighbor shooting a new pistol at cans on the fence post. We were dum by coming thru the woods instead of coming around and going down the fence line. Either way when I realized I was hit I thought I was gona die. As soon as my older cousin grabbed my arm he could see the lump(bullet) just under the skin. The neighbor loaded us in his truck and drove us home. My mother instantly started crying and panicking but when dad grabbed my arm and touched the lump the bullet fell out. Went to the ER and and absolutely no muscle or bone damage. That was 30 years ago and barely even have a scar. I've posted on here before about my buddy who was shot thru the armpit by a 270. He didn't even know he was hit by a rifle but as soon as he did he went into shock. The brain is a funny thing when it comes to being shot.

[mavracer]

I'm still guessing the shot took both lungs and bone, leaving the animal incapable of moving.

First deer I ever shot was hit with a 100gr 243 bullet at 200 yards, I ambushed it and it fell dead like the earth was pulled out from under it.
clean heart lung shot bullet entered behind the leg so nope no shoulder or any significant skeletal damage.

Dad shot a wild boar in almost the same spot with a 130gr 270 much closer again clean heart lung shot, no significant skeletal damage this animal seamed to think the report of the 270 was a starter pistol as he took off on a 200 yard dead run (pun intended) difference IMHO the boar had been chased by dogs into position and was pumped up. When we opened the chest cavity of that hog it looked like cherry jello the heart and lungs were 0% functioning.

[buck460XVR]

While I believe that hydrostatic shock happens to a degree from any bullet at virtually any speed, I doubt for the most part if it can be counted or relied on much for killing. It may make a wound worse and make a non-lethal wound slower and more difficult to heal, and may kill because of the infection caused by the increased damage, it ain't gonna make a difference between a bang-flop and a long blood trail with nuttin' at the end. As for how humans and deer react to hydrostatic shock, humans are wusses and will pass out from the sight of their own blood on their shirt. They react to pain by falling down and rolling on the ground. Look at European Soccer players.

[handlerer2]

Ever had the wind knocked out of you? I have seen a 220# athlete knocked to his knees and then all fours by a tap that didn't even leave a bruise. A half minute later he up and ok.

I think that many may confuse the effects of both. If your game takes trauma to the solar plexus, that is not immediately fatal, the reason he went down may not be due to hydrostatic shock at all.

I may be all wet, but I have been pondering whether if the sate of the respiration cycle may be a factor. If the thoracic cavity is inflated or deflated when hit by a bullet may be significant. If the animal is head up or head down may be also be a factor. The thoracic cavity is denser at the end of exhalation. It's less dense when full of air.

This becomes a complex problem even before you add blood pressure and CNS fluid pressure into the equation.


I have noticed over the years how many absolute authorities pontificate on different matters. I sure won't tell that this is way it is. I think none of us know without doubt why some game is DRT or gets up and runs off with similar tissue damage.

In my grandfathers time the chase after the shot was a part of the hunt. They didn't shoot at hundreds of yards and virtually never lost game.

[reynolds357]

With normal handgun calibers, you do not see the massive, jello like, wound channels and surrounding tissue you see with rifle rounds. The bullet hits, expands, and cuts a wound channel very similar to what you would see cut from a broadhead on an arrow. It tears up what it hits. You do not get the benefit of the near hit like you get with the magnum rifles. By "near hit" I will give an example of what I mean. I killed a very large bodied whitetail buck with a 7wsm 150 gr bst. I missed the heart by over 3 inches. 1/4 th of the heart, closest to the wound channel, looked like you had beat on it with a ball bat.
If you look at actual videos of police handgun shootings, the person hit does not even look like they were hit, spinal or brain hits being the exception. They are walking dead men, but keep coming. That is one reason police officers shoot people 3, 4, 5, 6, 7, or 8 times. If you simply hit vitals with a handgun, you will kill the person, but not stop them for quite a length of time. For a fast stop, you either have to disable the C.N.S. or you have to shatter major bones. Simply punching a hole in the lung, liver, etc. is not going to do it. The heart usually does not yield an instant stop.

[MarkCO]

I will try to explain, as clearly as I can why I think there is so much confusion in this area. I will, just for background give you some of my credentials at the end.

In the scientific realm, and in any pursuit that attempts to prove or disprove a theory, there has to be 3 major elements present. 1. Common understanding of terms. 2. A large enough data set from which to analyze results. 3. Repeatability of the method and or processes. Once we have those elements, the scientific method can be conducted. There are six steps to the scientific method and they are: observation, question, hypothesis, methods, results, and conclusion.

Hydrostatic is relating to or denoting the equilibrium of liquids and the pressure exerted by liquid at rest. So, when the term shock is added, it really becomes an oxymoron in general use. Shock, in the physical realm implies movement, but static implies no movement. So in reality, the "invention" and then gross misuse of this term is likely the greatest cause of confusion. However, as our testing and detection equipment has become more sophisticated, so has our ability to understand and categorize new observations. Put your ear on a railroad track...you can hear the train coming a LONG way before you see it...but even the highest magnification possible of a live SEM is unable to detect any physical change in the metal. Whereas a sound wave in air actually visibly moves molecules.

As for new terms, I would venture to assume that the majority of the people reading this were taught in school that there are three states of matter. It is now accepted in the hard sciences that there are actually 4 states of matter and we have some really smart men applying the scientific method (and they look to be right so far) to prove that there is actually a 5th state of matter.

Are there shock waves of various amplitudes, speeds and frequencies that travel through living tissue upon impact with a moving object? Yes, that can be proven. Does ballistic gelatin replicate those, and the mechanisms? No, that can also be proven. Ballistic gelatin can be used to compare bullets within a certain window and those results can then be projected on to a smaller data set of data from live tissue impact observations and or testing.

There is another very difficult problem when dealing with this subject. It takes medical and engineering (fluid dynamics, materials and ballistics) expertise, and at fairly advanced levels to be able to apply the principles and evaluate the date. So in most cases, it takes a team approach to develop a full understanding of the wound mechanisms and effects on living tissue then the impact that may have on the living organism.

Technology transfer is a term whereby proven methods, systems or operations are taken from one scientific field and applied to another. Since categorizing wounding theories and effects is expensive, time consuming, and for the most part not even possible, technology transfer is a good way to examine some effects. While I have participated in actual live testing, NDAs prevent me from even mentioning any of the elements, people, places, etc., however, the information learned gets to remain in my knowledge base. It is a rather simple matter to approximate impact pressures from bullets. It is then a rather simple matter to find other areas in which similar pressures have been used in other fields. The evaluation and relevance...that is a bit more tricky. Pressure, pressure waves and sonic waves have been used on a variety of meat animals both pre and post mortem in order to evaluate pain, killing efficacy and impact on the internal systems. The goal was processing, health benefits to consumers, texture and taste benefits to consumers and benefits of reduced cooking times. It is clear from the testing done that there are certain levels at which, while there is no visible effect, there was a derived benefit observed. Also, that at various levels, fibrous tearing occurs, cellular rupture occurs and eventually, liquefaction occurs. You have all likely eaten meat that had a shortened cook time, or a flavor alteration due to delivery of pressure and shock waves.

In the medical profession, study of volunteers in crash studies and concussion studies have been able to show that even with no cellular rupture, symptoms do occur in some subjects at certain levels. I am not a doctor, so I can not go into detail, but my general understanding as explained to me is that there is some level between rest and that which ruptures cells (physical damage) in which the "electrical" system of organisms can be short circuited due to pressure events. The affect varies, but can range from a chill, perceived vision flash, tingle to loss of consciousness and in rare cases, cessation of heart and lung function. At least with the other ballistics engineers I deal with in discussing terminal ballistics, it is in this realm, away from that area which suffers physical damage, where this term "hydrostatic shock" has been compartmentalized. None of the ones I have talked to believe that HS is completely reliable nor that is is, in and of itself a killing effect in most cases. When cells are ruptured, one can not term that hydrostatic shock since it is by its very nature dynamic. But the gunwriters, hunters, the majority of lay people and even some purported experts call all of it HS.

Also realize that the majority of the "ballistics experts" are not trained in medicine or engineering...the two fields from which the principles related to terminal ballistics are derived. The engineering and medical terms are often not the same and the crime lab folks borrow from both, but not based on science nor understanding in most cases.

There are multiple types of shock due to impact with an object, and additional types of shock if an object penetrates the flesh of a living organism. Drop in partial pressure of air in the lungs, drop in blood pressure in the circulatory system, psychological, CNS disruption by a variety of methods also occurs.

My education is in engineering (Colorado School of Mines and University of Colorado) with specialization in the thermal-fluid sciences, IC engines and materials. I did some graduate course work and then professional work on cell rupture theory, mostly in the area of microbiology. I have worked for the last 20 years as a forensic engineer. A court endorsed ballistics (as well as some other fields) expert, I have worked for plaintiffs, prosecutors and defendants in civil and criminal trials on a variety of firearms related and other cases including reconstructions. I have consulted for LE and manufacturers related to shooting, weapons, ballistics, design and materials. I am also a lifelong hunter who has shot a lot of game with bullets in testing, some of which did not come to market.

It is my opinion that Marshall and Sanow, started a good work, but with a very limited foundation. I have talked to Evan Marshall on a few occasions, and at one point he sent me a bunch of ammo to test, and I personally believe he tried to make sense of a subject that, at the time was not understandable by one person and lacking many tools now available. I have consumed most of the writings of the Medical professionals, and I believe that Fackler did great work in advancing the general understanding. But I still believe there is more to learn and that the general lay person is still largely making choices and having discussions based on flawed information. Many of the analytical techniques I use to study terminal ballistics were not even available 20 years ago when I graduated college. Even now, the computer time to run some simulations is so expensive, and with all the variables not being nailed down, in most cases it is just not economically feasible. There is still a lot to learn. But, I am not sure most of what will be learned will be of much value to the lay person.

My final thought is this...a handgun is a good compromise between a knife and a rifle...but sometimes you would have only been well served with a tank.