Hydrostatic shock

[plexreticle]

I was on another forum where someone mentioned hydrostatic shock in relation to ballistics is a theory.

I replied that it's an absolute fact, however, when I did some research it seems there are many that disagree.

What am I missing here?

Small fast bullet does more damage than small slow bullet. Tissue expands and contracts when hit by a bullet, the faster the bullet the more the tissue expands. Non compressible tissue like some organs just rip apart instead of stretching. Is this not hydrostatic shock?

I was under the impression hydrostatic shock is why a rifle is more effective than a handgun and why a handgun is more effective that a pointy stick.

 

[psyopspec]

Big, heavy, relatively slow calibers like .45 ACP in pistols smash the soft tissue they hit - it goes back to simple physics: Objects in motion remain in motion... and if that object is big and heavy, it's going to be harder to stop.

You're right that long guns will do more damage than handguns, but that's because they take heavy but slow/small but fast to extremes that far exceed the typical handgun caliber debates. I don't fully subscribe to either school of thought, as they both have plenty going for them. If you want a sidebar there's a 9mm/.45 thread going in the handguns section that also explores the contentions that are about to get going in this thread.

 

[plexreticle]

Thanks for the reply psyopspec. I'm not sure if my post really made sense but what I'm asking is:

Does hydrostatic shock exist?

Many would argue it doesn't. I was using the rifle vs handgun example to suggest it does.

 

[psyopspec]

Sorry, I misinterpreted your post. IMO, it does exist, and it's what I see on small game hunting videos when a coyote or bobcat gets hit in slow motion, and for a moment appears to increase in size by about 1/3 before dropping DRT. Unless what I've just described is something else, it certainly looks real and observable to me; there's certainly more going on in that case than the animal being hit in the vitals.

For further reading and a history of the debate:

http://en.wikipedia.org/wiki/Hydrostatic_shock

 

[61chalk]

I was reading about this many years ago, I am not 100% positive, but memory recalls that hydrostatic shock is what causes a shock wave to happen, moving through the body.
It is energy of the bullet that factors into this, as a example a .223 hitting a deer will have less hydrostatic shock than a 30/06 becuase the 30/06 has more mass an energy, the hydrostatic shock that produces the shock wave will actually stop, an sometimes reverse blood flow for just an instant, which can cause a heart attack. I see on videos deer being shot by large calibers, in slow mo you often can see the shock wave move through the animal, an notice alot of time it just drops dead right there. This is my understanding of hydrostatic shock....I am no expert, just what I read, I believe in Outdoors Life...anyone that believes I'm all wrong please way in, I'm eager to learn more...

 

[Oro]

The best way to think of this, in my opinion, is not to compare one bullet/caliber to another but to compare different projectile classes altogether. Then some useful inferences and comparisons can be drawn. A great example is a fast-pitched baseball.

If a major-league fast ball hits someone in the side, most of it's momentum will be transferred to the person. Think of a batter recoiling away from a bad pitch, the ball dropping to the ground. The resulting "shock wave" of energy will indeed pass through the person - but doing very little soft tissue injury other than the tissue right around the area struck and which was compressed. Yes, a nasty bruise will result, maybe a broken rib. Death possibly if the skull struck just so and fractured and driven inward. But people's livers don't burst or their hearts rupture because they get hit with a baseball. A .45acp contains about the same amount of kinetic energy as three major-league fastballs. A .45acp that penetrates through and through will likely take 50% or more of it's kinetic energy along with it as it leaves, meaning it deposited about as much as energy into a "hydrostatic shock wave" as a major league pitch, probably. But people don't wear Kevlar at baseball games...

The point is, human tissue has things that hold it together and make it resistant to deformation and permanent injury that ballistic gelatin does not. Cell walls, connective tissue, segmented body cavities, etc. Ballistic gelatin is one step removed from soup - human tissue and the human body is certainly not like that at all. Comparing cavities in gelatin and trying to equate that to permanent damage in a human is just ignorant of the physics involved and the anatomy of biological structures. The energy wave that passes through the tissue generally will fail to do what it takes to stop a living creature - tear up nervous tissue or tear apart enough blood vessels that the resulting pressure drop incapacitates the person. A powerful enough shock wave can indeed do this, but the average handgun round has no where near that much energy.

What any individual animal does when shot is certainly no guide to what happens in general. There was a post last weak of a skunk that took three shots of .45acp to stop it. So any individual case is vanishingly unimportant compared to a large body of samples.

The myth of "permanent wound channels" and pseudo-scientific mumbo-jumbo like that really seems to to just be that - mumbo jumbo made up to help sell ammo or articles, or explain squiggly bits of gelatin, but not something that plays out in real life.

 

[rmmoore]

To put it in simple terms so that "most" folks can understand (and I'm NOT saying most folks are simple minded, so don't go there), think of hydrostatic shock as the ripples that travel through a pond when you toss a rock in the air and watch it hit the water surface. The "waves" that ripple outward from the point of impact are a combination of kinetic energy transfer and displaced water from the object as it makes contact. As those waves get farther and farther away from point-of-impact, they get farther apart and "shorter" in height due to expended energy which causes the "ripples" to move slower, therefore diminishing their "effect" on the water's surface. As the rock moves downward, it obviously slows down for the same reason, loss of energy. I won't go into the effects of gravity, it would complicate a fairly simple explanation.

The "wound channel" from a bullet is largest at/near the point of impact because that is where the greatest energy transfer takes place, on/near impact. As the bullet travels through the target, and slows down, it sheds energy into tissues like the rock does in water, therefore the "wound channel" gets narrower as the bullet goes deeper into the subject and slows down. It's like looking at a tornado turned 90* on its side (<).

Although the principle itself is straightforward, the effects on a specific person have so many variables, there is no "standard" effect on a person, per se. However, consider the effect of a gut-shot animal when hunting. Upon opening of the chest/abdominal cavity, you find a bloody, gory ooze, almost like jello (yes, I HAVE gutted more than a few). That "tiny" bullet surely didn't do that much damage from the physical impact alone. As the shock waves rippled through its body (remember water surface on the pond, a body is much smaller and a closed system), the energy transfer compressed, and in many cases, ruptured/liquified the internal organs which are made up primarily of water. Guess what, the HUMAN body is the same. Again, no 2 people will respond/react the same way, although they may already be "dead" and just don't know it yet. Ever track an animal for hours to find it dead from only one shot?

Anyway, that is the quick and simple, along with a few examples. I am a believer in big, heavy, slow bullets rather than small, light, fast ones. The BHS ones want to stop immediately, and shed energy quickly; whereas the SLF ones want to keep going and do not expend energy as quickly, even though they may have MORE energy based on mass and velocity of the bullet. I'm not going to argue and start a caliber war, it is what it is. Pick what you prefer. Remember the example above: the more energy transferred into the target, the more devastating the outcome, even if it's NOT immediately noticeable. There are NO guarantees in life, no matter what you are shooting. But why take chances?

Another example of why I prefer BHS bullets: I personally know a Sheriff Deputy who early in his career was forced to shoot and eventually kill a druggie on PCP. Said druggie was shot 24 times in the torso before he was wrestled to the floor and died as he was being cuffed. Bullet? 9mm, 115gr JHP. This WAS a long time ago, granted, and the guy was as high as you can be. But, "I" personally have never heard of anyone requiring 24 rounds of 230gr .45ACP to be stopped, immediately or otherwise. I own a couple of 9mm pistols, and carry them ocassionally, when small size is a requirement. But they aren't my first choice, and are loaded with 147gr JHP bullets. Small and fast, but "heavier" than 115's.

 

[psyopspec]

To put it in simple terms so that "most" folks can understand (and I'm NOT saying most folks are simple minded, so don't go there), think of hydrostatic shock as the ripples that travel through a pond when you toss a rock in the air and watch it hit the water surface.

The big question is weather the ripples cause damage in soft tissue. If anyone had a definitive answer, it wouldn't still be a theory.

The "wound channel" from a bullet is largest at/near the point of impact because that is where the greatest energy transfer takes place, on/near impact.

The one time in my life I've gotten to see a bullet's effects up close on a human, the exit wound was significantly larger (5x or more) than the entrance wound. Bullet was FMJ 9mm, fired into the femoral triangle near the groin, exited below the buttock on the same side. Entrance wound was a small slit. Exit was a bloody crater about half the size of a fist.

 

[jbkebert]

A bullet passing through any matter will leave both a temporary cavity and a permanent cavity. If yu watch ballistics test using gelatin upon impact there is a huge displacment of the material and it shirnks back to roughly normal size. The displacment of the gelatin or temporary cavity is caused by hydrostactic shock. The trail you see when the gel shrinks back is the permant cavity. The act of the bullet dumping energy upon impact creats masive surrounding tissue damage beyond what is damaged by the actual bullet and its path.

 

[rmmoore]

Fair enough, I goofed and mis-spoke. Long day in the sun. You are correct on exit wounds, "most" of the time they are larger.

 

[The Lone Haranguer]

It certainly exists. Shoot a gallon jug full of water with a .45 Auto, then another with a .30-06. The one hit with the pistol bullet will just punch holes in the jug and spill the water, while the one hit with the rifle bullet will erupt and spray in a spectacular fashion. However, first, animals (and people) are not pure water internally. Second, even where it exists, the shock only affects the immediate area of the bullet's point of impact and travel through the body. You can't shoot someone in the little finger and kill them from the pressure wave through the rest of the body.

 

[Maelstrom]

I had taken hydrostatic shock to be similar to a sonic boom, but in a liquid medium instead of air.

A sonic boom is when a supersonic object compresses the air in front of it. Liquid, on the other hand, doesn't compress much and so the shock wave is more severe.

 

[hinton03]

The real issue is immediate effectiveness. No one gives a crap if someone dies from a wound due to damage caused by hydrostatic shock two hours after they have been shot, the point is to stop the assailant as soon as possible. To physically do that you must either damage the central nervous system or sever a major artery or organ that causes enough loss of blood to incapacitate the person (normally taking between 20 and 30 seconds).

Hydrostatic shock does neither as discussed in the FBI Handgun Wounding Factors and Effectiveness study shown at the link attached.

http://www.firearmstactical.com/pdf/fbi-hwfe.pdf

At least as important to stopping any assailant are the psychological factors associated with being shot; this is completely unpredictable since it is based on the persons state of mind, which can be altered by mental illness, drugs, etc.; however, studies show that a large percentage of people who have been non-fatally wounded immediately stop any activity other than trying to survive.

Basically, put one center of mass and your assailant will most likely stop in his tracks.

 

[The Lone Haranguer]

At least with handgun bullets, if you place a center of mass hit on the target but miss a vital organ like the heart by, say, an inch or two, what little hydro-shock there might be is not going to disrupt the heart's function. There is more of a chance of this with a rifle bullet, but still nothing to bet your life on.

 

[bigalexe]

If i may offer an insight into the Entrance/Exit wound difference ill cite my deer last October. I shot the deer with a Crossbow so its not a bullet but the same characteristics apply because it was hit with a projectile that achieved penetration in one side and out the other.

The Exit would was a bit larger than the broadhead and a little ragged. The entrance would was so small and clean we never found it. I dont think we would've found it either unless we had shaved the deer in the area it was hit it. There was no major bleeding to help either. Yes i am sure i was looking at the correct side and ill forgo explaining why because i dont think its relevant.

Anyway what i found even with the energy in a crossbow bolt at about 20 yards was that the exit was larger than the entrance. Now whether this is due to soft tissue ripping apart around the bolt as it went through the same as an airstream builds around a car on the road, OR if it was due to the fact that the broadhead was probably slightly dulled as it went through and the path was interrupted by the deer's innards is anyone's guess. If i had to choose i would say your Hydrostatic theory explains it better.

The only place that this theory seems to lose water in my head is with a fragmenting bullet that doesn't exit the target.

 

[61chalk]

bigalexe...arrows cause blood loss shock, not the hydrastatic shock wave of a bullet. Since the arrow is traveling in a certain direction, its naturual that matter will go in that direction upon exit following the arrow...I've shot some deer that the pass through was so fast that sometimes the exit wound wasn't much if any bigger than the entrance, but was readily found from the blood flow exiting. Now if someone comes up with a explosive tip arrow....now thats hydrostatic!!!

 

[psyopspec]

Exit wounds are a separate issue from hydrostatic shock, and more readily explained. Water doesn't compress, body is mostly water, a bullet is pushing forward and out as it travels through soft tissue, when it reaches the other side it's still pushing forward and out, so it makes an exit wound to reflect those forces.

 

[starkadder]

In my own studies of bullet wounds and terminal damage ( hunting many types of animals with both rifle and handgun ) I can say from experience that very few handgun rounds produce much in the way of hydrostatic shock, the only rounds that have any real noticable effect on surrounding tissue is the high velocity magnum rounds .357 and .44mag(with lighter bullets).

I have always studied the wound produced by my own guns, it's just how I grade certain rounds, and if it does'nt produce what I consider instantly lethal wound in an animal the it is safe to say that it will have the same effect on a human target. Now the other side of this coin is that an animal does not now that it has been shot, and if anyway possible it will escape as quick as it can, but people know that they have been shot and there is the mental effect that goes along with the actual wound.

I have seen first hand the effect of hydrostatic shock when a rifle is used, those of you who deer hunt know that if you hit a deer anywhere in the chest cavity with a 7mm mag or the like that all of the organs of the chest are jellyfied and will literally pour out when cleaning, BUT I have seen an animal hit like that run for 50 yards before it dies.

Hyrostatic shock is produced when a high velocity projectile strikes tissue and expands producing an larger frontal area and corresponding larger shock wave, or if the bullet fragments and does not pass through the target and expends all of it's energy on it, in my own experience a 30-06 is a very letal round(duhh) but growing up we used ball ammo to hunt with because dad was in the army and it was free, so he would file off the tips to the lead core, it was effective but not nearly as effective as say silver tips or core lockts because they tended to blow through without much expantion, and therefor not much hydrostatic shock.

As far as handgun rounds and hydrostatic shock, very few produce much regardless of the claims of the manufacturer, velocity is the key and very few have enough to cause any major effects. I am a firm believer in aim small, miss small, someone may have taken 15 plus rounds from a 9mm in his torso and extremities before he went down (would never trust my life to one in a combat situation) but a .380 FMJ to the face will end the situation.

This is this! It's not something else, it's this

Don't pull it if you don't plan to use it, and don't use it if you don't plan to kill

ALWAYS REMEMBER OUR MEN AND WOMEN OVER THERE.

 

[psyopspec]

Hyrostatic shock is produced when a high velocity projectile strikes tissue and expands producing an larger frontal area and corresponding larger shock wave, or if the bullet fragments and does not pass through the target and expends all of it's energy on it,

You're saying that bullet expansion and/or bullet fragmentation = hydrostatic shock? I'm not so sure.

If hydrostatic shock is actually a real phenomenon, I would think it would be best demonstrated in fast rounds that didn't expand or fragment, in order to keep the "lethal shockwave" going.

 

[jbkebert]

Now if someone comes up with a explosive tip arrow....now thats hydrostatic!!!

Rambo had'em heck they could shoot down a soviet helicopter


Really though the actual effects of hydrolic shock are hard to measure in something like a deer. A well placed chest shot enters the thorasic caviety which is mostly hollow and surrounded by hollow organs, (the lungs) the displacment of organs and trauma will be somewhat limited. Now take a poor shot or paunch shot if you take your time and disect the wound channel you will see massive tissue damage well away from the bullet channel. Organs in this area will somewhat more solid and will be more prone to notice damage and movement.

 

[RyanM]

The effect sorta exists, but the nomenclature is off. Most sciency types prefer "cavitation." The bullet accelerates target material outward, making either a temporary cavity (if it snaps back into place, like if you yank on the skin on your arm) or a permanent cavity (if tissue is stretched beyond its elastic limit, and tears).

The volume of the cavity made by a bullet is almost directly proportional to its energy, so rifles make much bigger cavities. Most rounds below about 800-1,000 ft-lbs only make a temporary cavity (it's not big enough to tear anything) in something the size of a human or deer. So with pistols, energy is practically irrelevant, as 400 ft-lbs on a .45 ACP will make a bigger hole than 800 ft-lbs on a .22 cal bullet.

With rifles, it starts to matter more.

 

[starkadder]

Phyopspec, you are right to an extent in that fast solid projectiles produce a shock wave for a longer period of time in the target, but that wave is relative to the size of the frontal area of the bullet, that is why super sonic aircraft are pointed at the front.

The shock wave is going to be produced at high speed but a smaller frontal area reduces its effects and spreads it around the object, if a super sonic jet had a rounded nose like that of a .45 the produced shock wave would probably crush the nose because of the amount of pressure generated at the frontal area, the sonic boom is the effect of the shock wave being overcome and "broken" as a high velocity pointed bullet does.

Now on that note I have shot jack rabbits with 5.56 SS109 that literally exploded, but the effects are all relative to size and mass of both target and bullet.
A person shot with the same round may not even know that they are hit unless a major organ, area of heavy muscle mass, or bone is hit, but if a person was shot with a varmit type round or a soft point 5.56 hunting round the effects would be severe and undeniable.

This is this! It's not something else, it's this

Don't pull it if you don't plan to use it, and don't use it if you don't plan to kill!

ALWAYS REMEMBER OUR MEN AND WOMEN OVER THERE.

 

[Shadow 7D]

this is from a medics perspective, not looking at dead animals (BTW the effects of temporary cavitation are only apparent under microscopic examination, and even then there is debate)

2 types of wound track: permanent and temporary

hydrostatic shock is tectonically the method of creating the temporary track.
Most body tissues are VERY elastic and simply get pushed out of the way, you can have some bursting effects on blood vessels and similar.

the hard tissues are those most damaged by the temporary track, ie bone and liver, a fragmented bullet, or otherwise deformed does not impart more "shock" rather it disrupts (meat grinder) more tissue and that causes more blood loss. It is to the point that major medical journals have printed articles about whether or not to debreid GSW, especially low velocity pistol wounds. As far as the "shock" and CNS disruption..... I got a .50, howbout I shoot you in the finger and see if you get knocked down and your arm tore off. I'm not saying hydrostatic shock doesn't exists, ask any redneck who fishes with dynamite, just that the jury is in the octagon and the fight is rather dirty.

 

[Black Dime]

Put a gallon jug on top of a cinder block with the holes in the block horizontal. Shoot the jug with a 30-06, 7mm mag, 308,........
The resulting pieces=hydrostatic shock.

"The term hydrostatic shock describes the theory that a penetrating projectile produces remote wounding and incapacitating effects in living targets, in addition to local effects in tissue caused by direct impact, through a hydraulic effect in liquid filled tissues. There is scientific evidence that “hydrostatic shock" can produce remote neural damage and produce incapacitation more quickly than blood loss effects. The debate between proponents of bullets that are "light and fast" versus bullets that are "slow and heavy" often refers to this phenomenon."

Not about which is best for deer killin', but an argument by the fast and little will cause HS.

In my opinion, HS does not leave "evidence". The horrorific tissue expansion quickly returns to normal minus the effect of the bullet hole.

 

[RP88]

hydrostatic shock does exist, but it is not some guaranteed force that can be triggered by the size and energy deposit of a bullet. It is also a force that is dependent on the would-be target's mental and psychological condition and sheer willpower to continue fighting or fleeing, or how much energy is deposited. Usually, it is not going to be a 100% probability unless you have a VERY powerful bullet and good shot placement. But even then, the sheer shock of critical organ loss is going to take more of an effect than anything else.

The real argument about hydrostatic shock's existence is if it exists in handgun cartridges, and if it happens consistently or reliably enough (pretty much one-half of the 9mm/40/45 debate). Considering how unreliable most handgun rounds are as one-hit stoppers, I'd wager a "no" as my answer.