So hydrostatic shock...

[HALL,AUSTIN]

Is speed the sole factor here? Does weight come into play? I know it's all about putting the bullet in the right place but I'm trying to learn a bit more about hydrostatic shock.

[bamaranger]

I think the idea of a bullet creating some type of shock wave the short circuits a critters system via sometype of "pulse" is largely exaggerated.

We can see examples of terrible explosive wounds on smaller critters with very fast small bullets, and similar damage on larger critters with really large caliber (.50BMG) but beyond those extremes, many bullet wounds look a lot like another regardless of caliber. And some solidly hit animals drop at the shot, others sprint away wildly, regardless of caliber.

I believe the condition of the animal (relaxed v. adrenalin charged) and the nature of the shot (close range with loud blast v. longer range and quieter), as well as whether or not the central nervous system is disrupted, play largely into how an animal behaves when struck. I think shots close to the spine, can drop an animal due to a shock to the spinal cord, but undamaged, an animal can recover its feet and escape from wound that does not damage the spine or underlying organs. I also believe an animal can drop due to major shoulder bones or hips being broken, but I suspect this is a balance thing and not so much blow. Mortally wounded shoulder or hip shot animals can recover to their feet to cover some distance before expiring. Note here I mean through a single shoulder or hip.

[Old Stony]

I shoot lots of hogs and can plainly state that a hog shot through the neck with a small fast caliber is more likely to drop quickly, than one shot through the lungs with a large caliber. The shock to the CNS is a big factor in dropping one on the spot. I love more fragile bullets for this sort of shooting, especially the Hornady SST. When I shoot large calibers, I try for shots through the front shoulders to stop them....but they do live longer when shot in this manner.

[HALL,AUSTIN]

I found this, it was a bit long but a nice read. Old Stony have you neck shot any hogs with a larger caliber?


http://www.ballisticstudies.com/Know...e+Killing.html

[ZeroJunk]

P. O. Ackley thought the RPM of the bullet had something to do with it. I'm nobody to argue with him.

[ShootistPRS]

"hydrostatic" shock is a name given to an event caused by the supersonic movement of fluids by a fast moving projectile. You said you wanted to learn about it well this is the truth:
"hydrostatic" shock is neither a static event nor is it a shock. The bodies of animals is mostly salt water. There are fibers and organs that are flexible and suspended in and filled with fluids. When a bullet of sufficient diameter enters a body at supersonic speeds there are a few things that happen very quickly. The leading edge shock wave pushes stuff away from the path of the bullet. Experts call this the temporary wound channel but there is little wounding taking place. This is a dynamic and elastic motion and rarely causes more than a bruise in the local area. At the same time the bullet itself ruptures tissues as it goes through them. This causes bleeding and deep tissue damage. This is what kills the animal. While that is happening the back of the bullet drags a cavitation wave behind it that lowers the pressure momentarily causing "bubbles" similar to boiling but without the heat. This tends to cause the tissues to pull back into the lower pressure behind the bullet collapsing the temporary wound channel and slightly increasing the bruising.
Normally the only killing mechanism is the actual hole and damage that the bullet makes as it cuts through the tissues. There are times - however rare they are that the compression wave hits the heart at the instant it is compressing and causes very high blood pressure throughout the animals vascular system that sometimes causes hemorrhage in the brain. The animal collapses so fast that it appears to be knocked over by the impact.
We can see the hydrostatic shock is neither static (without movement or change) nor a reliable killer. It is reliant on two things;
1. speed over the speed of sound
2. the physical size of the projectile
If you can imagine a sewing needle at 20,000 feet per second going through a deer you can "see" that there would be very little tissue movement and very little damage to organs. The needle would go right through and the animal might or might not be aware that it was shot. The small wound would heal in a day or so and the animal would be unaffected.
a 30 caliber bullet hitting the animal at 2300 fps will produce a large frontal compression and cut a hole through tissues big enough to provide for a loss of blood that will kill the animal.
A 12 pound bowling ball traveling at 300 fps will break bones and cause huge ruptures in tissues that will kill the animal quickly even though it is not travelling anywhere near the speed of sound. The internal damage will be caused by broken bones cutting and tearing the inside of the animal.
The truth behind "hydrostatic shock" is that it is a made up name for a reaction that has little value in the quick and clean killing of a game animal.
I hope this gives you the information that you are looking for.

[603Country]

P.O. Ackley sang the praises of the 220 Swift and hydrostatic shock when used on deer. So, I took my 220 Swift deer hunting (60 gr Nosler SBB and Sierra 63 gr SMP). I shot a few deer that dropped like they had been electrocuted and I shot a few that didn't seem to notice that I had shot them. I finally decided that if the hydrostatic shock isn't applied to the proper place, it isn't much use. Perhaps if a fellow used a big enough bullet at a fast enough velocity (270 or 257 Wby), hydrostatic shock can be 'applied' over a larger area and will be more effective. That said, nothing I ever used was more effective on deer than my old 35 Remington, and I don't expect that it was so effective due to hydrostatic shock.

A big fast bullet kills better than a little fast bullet, and is probably a bit less dependent on the best of bullet placement.

[FrankenMauser]

I'm a believer in the theory. I've seen it first-hand.
...But it doesn't seem to be predictable.

Speed seems to be necessary. From what I've seen, I'd say 2,600 fps or faster.
And I've never seen it with anything but expanding bullets.

But, I think people get a little too hung up on the 'nervous system disruption' and forget about the rest of the concept, whereby the hydraulic pressure wave damages soft tissues.


In ... 2009, I think, I shot an antelope with a .277" 130 gr Remington Core-Lokt. Clean double-lung. Small entry. Small exit (~.54 cal). No fragments to speak of.
Liver was "shattered" from the shock wave -- literally torn into chunks with radiating lines of cleavage reminiscent of it having been frozen and smacked with a hammer. Quick death due to massive internal bleeding and hypoxia, but not a "DRT" or any indication of nervous system disruption.
That liver was a surprising find in the gut cavity of an animal that had no damage to the diaphragm or guts.

Come to think of it, that wasn't the first one, either.
In 2008, one of my brothers punched a broad-side antelope right through the heart with a .277" 140 gr Nosler Ballistic Tip (hunting version). That was one of the most impressive DRT shots I've seen. That speed goat dropped like a rock and never so much as twitched after it hit the ground.

In that case, I do believe there was nervous system disruption, but the bigger surprise came from the Ballistic Tip seeming to penetrate through all of the muscle and then "detonate" just outside the heart in the left lung. The base continued through the animal and exited with a ~.70 caliber hole.
Heart and lungs were just soup with some bullet fragments mixed in. The liver, just as we would find the next year, was absolutely "shattered", even though no bullet fragments had touched it and it was on the other side of the diaphragm.

And, since then, there have been a few more speed goats and elk that showed signs of the shock wave doing significant damage.

I have never seen a "tough" bullet do it, though -- things like Nosler Partitions, Norma Oryx, etc.
And even nearly identical shots on the same type of game, with bullets that have gone "hydrostatic" in the past, may not give the same results.


All anecdotal evidence and my opinion... Take it for whatever it's worth to you.

[jmr40]

Speed AND bullet construction are the key. A FMJ that does not expand doesn't cause much hydrostatic shock. A soft bullet designed to expand at relatively slow speed can cause a lot of damage at slower speeds.

The key is to understand what the bullet you are using is designed to do and not ask it to do something it wasn't meant to do.

There are 2 schools of thought, both work, both have negatives. Some guys like a softer bullet that expands violently. If put into a game animals vitals those bullets take down game quickly. Softer bullets work very well at longer ranges where they will still expand after slowing down. But if pushed too fast will blow up at close ranges and not give enough penetration to reach vital organs. They may not be the best choice for larger game where bullets may have to penetrate 2-3' in order to hit vitals. Especially if shot from less than perfect angles. Soft bullets CAN penetrate well enough if using heavy for caliber bullets fired at moderate speeds.

The other school of thought is to use a harder bullet that penetrates deep. Those bullets tend to work, but rarely put game down in their tracks because of less hydrostatic shock. They are not the best choice for long range shots. After slowing down they may expand very little and cause little damage. But are generally considered a good choice on larger game.

The cartridge used is important. A soft 150 gr bullet fired at 3300 fps from a magnum rifle would actually be a poor choice on deer inside of 100 yards. Too much expansion, too little penetration. But the same bullet fired from a 308 at 2800 fps would work great.

[ZeroJunk]

Not an exact science, that's for sure. I shot a doe through both lungs broadside with a 150 grain Hornady, whatever Weatherby used in their factory loads. Supposed to be 3500 muzzle. I was lucky to find the deer since she ran a couple of hundred yards with little to no blood. Bullet went straight through, no expansion. The deer I had shot previously pretty much never moved another muscle. I'm sure it just slipped between the ribs. That is how the stories get started about bullets that go through a deer too fast to expand, although I can't say that I buy that.

[Lohman446]

Not an exact science, that's for sure. I shot a doe through both lungs broadside with a 150 grain Hornady, whatever Weatherby used in their factory loads. Supposed to be 3500 muzzle. I was lucky to find the deer since she ran a couple of hundred yards with little to no blood. Bullet went straight through, no expansion. The deer I had shot previously pretty much never moved another muscle. I'm sure it just slipped between the ribs. That is how the stories get started about bullets that go through a deer too fast to expand, although I can't say that I buy that.

When I was younger I jumped a BIG doe on the way to my stand. I took one of those shots that you shouldn't take and effectively instinct shot it with a .270 (I think some Winchester Failsafe ammo back in the day). It was quartering away and it was a lucky shot. The thing ran about 200 yards through some heavy brush and it was not easy to track as there was very little blood for the first 50-75 yards. When I gutted it I could not identify much in the way of the lungs or heart - they kind of "poured" out. Utterly amazed at how far that deer had run. Of course it was startled so that might have had something to do with it.

[FrankenMauser]

Oh, I just remembered another really surprising one.
Don't recall who shot it, or what year it was, so I'm not sure what the bullet was. (But likely 7.7x58mm Jap, .270 Win, or .30-06.)
Doe antelope, quartering heart/lung shot.
Don't think it was a DRT.
When we went to field-dress her the heart and lungs were soup. Not much of a surprise.
But the liver and kidneys were ruptured. They looked like they had "popped" like over-inflated beach balls. The kidneys blew us away. I believe cornbush (TFL member / my brother) has a picture of those kidneys somewhere.
It was an interesting find.

[ZeroJunk]

When I was younger I jumped a BIG doe on the way to my stand. I took one of those shots that you shouldn't take and effectively instinct shot it with a .270 (I think some Winchester Failsafe ammo back in the day). It was quartering away and it was a lucky shot. The thing ran about 200 yards through some heavy brush and it was not easy to track as there was very little blood for the first 50-75 yards. When I gutted it I could not identify much in the way of the lungs or heart - they kind of "poured" out. Utterly amazed at how far that deer had run. Of course it was startled so that might have had something to do with it.

The thing about the "autopsy" on the deer shot with the 300 WBY was that there was really no internal damage other than the caliber size hole.
She ran until her lungs filled up. That was it. More like being shot with an arrow using a field point.

[briandg]

Hydro-static-shock involves the shock, or pounding, those tissues receive when water is forced aside by explosive compression of tissues because of impact. In truth, hydrostatic shock is horribly overrated. Any bullet causes impact and "shock" as it passes through and displaces water and tissue, but it may be minimal to almost non existent. Some rounds will literally explode into fragments.

Shock itself can cause bruising and breakage of small blood vessels or other tissues, but that doesn't really make much difference until you have increased your velocities between levels by 300 fps, maybe. the .45 acp is about 850 fps and the colt is about 1,100, and if you check with most people, they will agree that they will both cause about as much damage in a solid slug. It takes a large increase in velocity for a solid slug to be improved by velocity alone.

Frankly, i feel that there are other more important things to consider. Bullet design, and whether or not the ammunition is appropriate for the expected use. Shock is a nice thing, it causes pain, bleeding, etc, but what really kills things/people is either destruction of organs or vital areas, or bleeding. No matter how much shock you put into a chunk of butt with a varmint cartridge, tearing out a half pound of meat won't kill a man. same thing goes for hitting him in the butt with anything, pretty much.

When you get chest cavity hits, punch holes through innards and lungs, veins, etc, you have started the ball rolling. an expanding bullet makes the hole bigger and it displaces more water as it goes through. the faster the bullet is moving, the more violently that water is displaced. So, a mushrooming bullet that is moving faster will almost inevitably cause more damage than an otherwise identical, slower, non expanding round.

I feel like a pistol round becomes effective when it passes 1,000 for example, it needs a certain level of speed and energy to expand a bullet and poke a big hole.

A rifle round is different, bottle necked, long, heavy, narrow bullets, I feel that a standard rifle round needs about 2,000 fps to really expand and add anything to the wounding. Low velocity, non expanding rounds aren't even as good as being hit by an arrow. The .30 carbine or .38 special lead load are notorious for ineffectiveness. It left little holes like a screwdriver would leave. The typical deer broadhead cuts a bleeding channel through the tissues over an inch in diameter. No need for high velocity impact, good god, that thing rips a hole through a deer that can bleed it out in a matter of minutes in a good area.

Once you reach a certain threshold of velocity, construction, point of impact, the shock, or hammering effect can cause serious, serious damage. Look at a prairie dog or ground hog that was shot with a .22-250. That is all about high velocity hydrostatic shock. then, shoot the next one with a plain .44 magnum. You can dump an enormous amount of energy into a small area, or you can let it escape out the back door.

[Sure Shot Mc Gee]

Speed has more to do with hydro-static shock than bullet weight. I found 3200 fps at muzzle is the magic number I strive to get my 243/270/25-06 up too and exceed if possible.

[ShootistPRS]

For anyone who wants real test results I suggest reading the foremost experts studies on the subject. His name is Dr. Martin Fackler. His obituary can be found here.
One of his articles on the myths and lies of wound ballistics can be found here.
You are free to disagree with the facts that this surgeon and scientist has provided the shooting industry if you think you know more than someone with his involvement in the study of terminal ballistics. I choose to defer to his research and knowledge.

[Old Stony]

Hall,Austin.....I've shot them in most spots with a myriad of calibers, but the neck seems to be the easiest spot for me to drop them quickly. Using 45/70's I normally just shoot them through the front shoulders. I really don't study the dynamics of bullets and calibers much....I just shoot'em and move on.

[ZeroJunk]

I'm not sure how the military wound discussions relate to hunting bullets, or commonly used civilian pistol bullets for that matter.

[doofus47]

I think that there's something to the idea of shock doing damage. Witness the occasional story of a little league kid taking a baseball to the chest and having heart arrhythmia.

I think it depends where it hits you. I think of the blood-shot meat that I cut away from wound channels. I don't think that the busted capillaries are going to be fatal, but a bruise of damaged flesh is still a bruise. I think that if that shock bruised a heart or a lung or an aorta on the way through, that can't help.

[briandg]

There is another thing to consider, every bullet impact severs nerves. While a huge temporary cavity will damage some tissues such as veins, it will also tear apart fragile nerve tissues.

After carefully considering all of the amazing things that bullets do, I'm left wondering, how in heck do those things manage to get up and run away? you ought to be able to hit a deer in the ankle and have it die before it hits the ground! Stupid critters didn't get the memo.

[Scorch]

Hydrostatic shock is a very real thing, it is the energy transmitted to an animal through its own body fluids reacting to the impact of the bullet, primarily when the fluids cannot move out of the way fast enough. You can see it when you shoot a deer with any relatively fast-moving bullet, you will see a wave of ripples move away from the point of impact and dust, water, mud, hair fly off the animal. The most visible effect of hydrostatic shock in harvested game animals is blood-shot meat. So, yes, it exists and has a real effect on any animal when that animal is shot with a high-velocity projectile.

Having said that, the idea that the energy from the bullet hitting the animal can disrupt its neural pathways, stop its heart, drop it where it stands, or any other nonsense of the sort, is preposterous. To take it a step further, the idea that a bullet merely passing close to a game animal can kill it is akin to believing in the tooth fairy.

On the other hand, big proponents of hydrostatic shock kills were Roy Weatherby, Parker Ackley, and Charles Newton, kind of a "Who's Who" of the gun world.

[briandg]

Elmer Keith told a story of a tick bird that fell off of a buffalo he shot, dead. I don't want to call him a liar.

It's true that the term shock is improperly used. In this case it refers to a shock wave. It also refers to systemic shock, or the sort of shock yo feel when unexpectedly taking a serious injury. You also have another type of shock, the type of medical shock when extreme injuries are causing the system to die.

The Keith bullet was the first design tha added shock waves to the impact, instead of just a round ball.the flat gameplay, the sharp shoulder, both contribute to an outward push of fluid. Is that significant? I think that the damage is better attributed to the sharp flat profile cutting a better hole.

There is no "shock," like a lightning bolt, that sends a killing burst of energy to the brain and drops the beast instantly. Sure, it happens.It is not normal.it's luck if that's what you want to call it.

[Jim Watson]

I vaguely recall a report from Sweden that the minimum velocity for shock or "pulsatile cavern" effect was 2650 fps. Hmm, about like a 6.5x55.

[HALL,AUSTIN]

Jim the link I posted also cites that exact velocity. It seems opinions vary or at the very least it is situationally dependent on a plethora of variables as far as if it aids in a quick kill or just some extra trimming of harvested game.

[MarkCO]

Having read all of the responses in this thread, and having actual expertise in the field, Scorch's post is the most accurate for the application to the average hunter.

MUCH has been learned since Fackler last wrote about the phenomenon. Being the first expert in the country to prove entrance velocity based on virtual autopsy, I had to do a lot of work in the area before a judge would let me talk about it. There are still several unknowns related to the actual effect and it certainly varies in each specific case. Reliance upon hydrostatic wave propagation as a method to kill game animals is a fools errand though.

But the answer the OPs question, frontal area of the projectile IN the animal being shot is part of the equation. A minimum impact velocity of 2200 fps has been cited by some experts, but I believe there is a range as well as a distance from the CNS and heart that is also a part of the equation. What becomes difficult is separating mechanical trauma from a bullet from a (less specific) CNS or heart disruption from a shock wave.

Several years ago I worked tangentially on a DARPA project that used stand off wave propagation to neutralize living things. It was pretty effective on small targets, less so on large targets. In any event, some of the shock wave propagation theories were validated. I have no idea where that system is today since it was generally deemed "inhumane" for the battle field.

The frequency of a wave propagating (and attenuating) through a living thing and at the point (for the heart) in the cycle it first encounters an organ which it may disrupt is part of the equation as well. A few milliseconds earlier or later and the disruption may be negligible as opposed to disrupting the electrical cycle. The electrical system in the heart is an amazing thing. There have been cases of living things being shot and the bleeding was minimal and upon post mortem examination, the heart is full of blood as is most of the body...implying the heart stopped pumping at the time of bullet impact. In similar impacts, it was clear that the subject bled out...meaning the heart was pumping.

I hope that this discussion helps explain why there is a lot of misinformation on the topic and actual observations that seem to suggest it is real, and it is false. I fully believe it is real, but I also fully believe that it is unreliable and a bit of a gamble as to whether or not it will have any influence in a specific instance.