If hydrostatic shock were a fact??

[stag1933]

I once called my lady companion a `stupid cow` and she smacked my ear !
If I had called her an`oxymoron` she might have thought this complementary and given me a kiss.
With threads like this I wonder how I have successfully shot seven species of Deer in 51 years only believing that we kill them by destroying living tissue.

HWH.

 

[j0e_bl0ggs]

Hydrostatic - what exactly is static then?

 

[Ulfhere]

Ok... I get that (mostly! ) so the question is then, is the debate as to whether hydrostatic shock is real or not just a terminology issue? The dynamic pressure wave appears to produce quite violent cavitation in the jelly, would this wave and subsequent cavitation be strong enough to rupture vital organs or even break bones as has been suggested?

Vipa, localised high pressure induces strain that results in maceration of soft tissue and shattering of bones (a bullet has to pass very close to bone to break it) - but this is local to the passage of the bullet. It is caused by direct conversion of pressure to stress in the tissue (same units) resulting in plastic strain and to a lesser extent by momentum transfer to the displaced tissue which can result in tearing as it translates away from the shotline. Neither heat nor phase change play any meaningful or observable role in wounding. I have never seen any evidence of that. If that occurred it would be evident in gelatin tests.

The key thing is to remove the mythology about some mystical effect that "shocks" the game to death. Its pure mechanics. Everything that happens is a consequence of localised pressure on vital organs. If that occurs in or very near a blood filled heart then it can explosively burst. Same with the lungs. Hydraulic pressure on the major arteries to the brain can in rare instances cause instant death. Higher velocity results in dramatically higher pressure. It also results sometimes in violent deformation of the bullet. So, to be fair, this is where the legend was born, with bullets that basically went to bits in the heart-lungs area, creating a very large pressure zone that destroyed those organs instantly. But what has also been learned is that, however spectacular that may be some of the time, it is not a situation you want to depend on because it can also go horribly wrong if the bullet disintegrates without reaching vitals (in a strong shoulder or by passing through the paunch first, for instance). A better bullet will usually be less spectacular but much more dependable.

Hydrostatic shock does not exist - it is an impossible state, a terminology concoction of gun writers, not scientists. However, it is an attempt to describe the behavior of game subjected to extreme cavitation. If we speak of hydrodynamic pressure resulting in cavitation, then we are correct. No hype or ballyhoo, just ordinary mechanics.

If all this seems a bit like a dog chasing its tail, I apologize. When I first wrote my piece attempting to refute the misconceptions my intent was foremost simply to clean up the language and begin afresh with correct physics and physiology so that a better understanding could be had. That is the issue with "hydrostatic shock". Secondly, I have tried to debunk some of the mythology, but in doing so it is necessary to explain the real mechanics that do occur. Sometimes I think those two distinct concerns become confused or seem contradictory. For that I can only blame my limited ability to communicate and clarify.

 

[Vipa]

Vipa, localised high pressure induces strain that results in maceration of soft tissue and shattering of bones (a bullet has to pass very close to bone to break it) - but this is local to the passage of the bullet. It is caused by direct conversion of pressure to plastic strain in the tissue (same units) and to a lesser extent by momentum transfer to the displaced tissue which can result in tearing as it translates away from the shotline. Neither heat nor phase change play any meaningful or observable role in wounding. I have never seen any evidence of that. If that occurred it would be evident in gelatin tests.

The key thing is to remove the mythology about some mystical effect that "shocks" the game to death. Its pure mechanics. Everything that happens is a consequence of localised pressure on vital organs. If that occurs in or very near a blood filled heart then it can explosively burst. Same with the lungs. Hydraulic pressure on the major arteries to the brain can in rare instances cause instant death. Higher velocity results in dramatically higher pressure. It also results sometimes in violent deformation of the bullet. So, to be fair, this is where the legend was born, with bullets that basically went to bits in the heart-lungs area, creating a very large pressure zone that destroyed those organs instantly. But what has also been learned is that, however spectacular that may be some of the time, it is not a situation you want to depend on because it can also go horribly wrong if the bullet disintegrates without reaching vitals (in a strong shoulder or by passing through the paunch first, for instance). A better bullet will usually be less spectacular but much more dependable.

Hydrostatic shock does not exist - it is an impossible state, a terminology concoction of gun writers, not scientists. However, it is an attempt to describe the behavior of game subjected to extreme cavitation. If we speak of hydrodynamic pressure resulting in cavitation, then we are correct. No hype or ballyhoo, just ordinary mechanics.

If all this seems a bit like a dog chasing its tail, I apologize. When I first wrote my piece attempting to refute the misconceptions my intent was foremost simply to clean up the language and begin afresh with correct physics and physiology so that a better understanding could be had. That is the issue with "hydrostatic shock". Secondly, I have tried to debunk some of the mythology, but in doing so it is necessary to explain the real mechanics that do occur. Sometimes I think those two distinct concerns become confused or seem contradictory. For that I can only blame my limited ability to communicate and clarify.

So... to conclude (from my point of view anyway...) Hydrodynamic pressure and the resultant cavitation are quite capable of causing serious damage to vital organs and killing a beast in thier own right as opposed to high velocity bullets just being a more efficient method of creating a wound channel compared with say, a broad head arrow and thus causing a catastrophic drop in blood pressure, bringing on rapid unconciousness and then subsequently bleeding out?

Terminology aside, this is where the two camps in the discussion the 'discussion' ended up being polarized.

 

[Tom D]

I really like this guy's site, he certainly seems to have shot a lot of animals, and he appears to take an interest in the effects of different bullets and calibers on the internal organs. This is a good article.
Part 1 Game Killing

 

[MarinePMI]

Hydrostatic - what exactly is static then?

Uhh...the (mostly) liquid medium (i.e. tissue)?

I won't get into a semantics debate, and agree with Muir: there is no magic bullet, shot placement counts.

Of interest however, was an article I recall reading that involved culling wild buffalo and horses. Some just fell over after being shot, and others managed to walk a little before dying (even with killing shots through the heart); with no apparent reason as to why there was a difference.

After this discrepancy was noted, the author inquired to the local DFG veterinarian to perform necropsy (after taggin which animals had died "instantly" versus those that had not). After dissection he found that when looking only at animals that had fatal shots to the heart, those that had been tagged as "DRT" suffered from severe hemorrhaging at the base of the brain cavity. Those that wandered a bit before dying did not.

When further analysis was done on those animals that had severe hemorrhaging, it was found that the main arteries that transported blood from the brain were found to have the valves within them, completely torn and damaged.

His theory/conclusion was that those animals that had suffered from hemorrhaging and torn arterial valves and shot in (or around) the heart, had been shot at the exact moment that the animals hearts had contracted, and had began expansion. As such, when the heart was contracted and began to expand, the valves on the arteries returning blood flow were extended to prevent back flow to the heart; and these were impacted by the shock wave of the bullet, violently pushing blood into the brain cavity, causing severe and immediate damage to the brain stem. Essentially, this killed all the basic functions of the brain (breathing, muscle control etc.) and gave the appearance (if not in reality) that the animal just fell over dead from the "shock" of the bullet. He theorized that this is where the often disputed "myth" of hydrostatic shock came from, and how there were very highly respected and professional hunters who claimed it existed and similarly, others (equally respected) who said it didn't.

He further concluded that there was no way possible to prove this in the field, and that it would require extensive (read: expensive) equipment and environments to conclusively prove his theory.

Now I don't know if this is a valid theory or not...but it does make some sense to me and my little pea brain.

 

[j0e_bl0ggs]

Uhh...the (mostly) liquid medium (i.e. tissue)?

I won't get into a semantics debate

I understand your reluctance.
Ahhh so no "(mostly) liquid medium (i.e. tissue)" moves then?
Incredible these static pressure waves eh?

 

[j0e_bl0ggs]

Of interest however, was an article I recall reading that involved culling wild buffalo and horses. Some just fell over after being shot, and others managed to walk a little before dying (even with killing shots through the heart); with no apparent reason as to why there was a difference.

After this discrepancy was noted, the author inquired to the local DFG veterinarian to perform necropsy (after taggin which animals had died "instantly" versus those that had not). After dissection he found that when looking only at animals that had fatal shots to the heart, those that had been tagged as "DRT" suffered from severe hemorrhaging at the base of the brain cavity. Those that wandered a bit before dying did not.

When further analysis was done on those animals that had severe hemorrhaging, it was found that the main arteries that transported blood from the brain were found to have the valves within them, completely torn and damaged.

His theory/conclusion was that those animals that had suffered from hemorrhaging and torn arterial valves and shot in (or around) the heart, had been shot at the exact moment that the animals hearts had contracted, and had began expansion. As such, when the heart was contracted and began to expand, the valves on the arteries returning blood flow were extended to prevent back flow to the heart; and these were impacted by the shock wave of the bullet, violently pushing blood into the brain cavity, causing severe and immediate damage to the brain stem. Essentially, this killed all the basic functions of the brain (breathing, muscle control etc.) and gave the appearance (if not in reality) that the animal just fell over dead from the "shock" of the bullet. He theorized that this is where the often disputed "myth" of hydrostatic shock came from, and how there were very highly respected and professional hunters who claimed it existed and similarly, others (equally respected) who said it didn't.

He further concluded that there was no way possible to prove this in the field, and that it would require extensive (read: expensive) equipment and environments to conclusively prove his theory.

Now I don't know if this is a valid theory or not...but it does make some sense to me and my little pea brain.

I guess a fatal heart shot might produce some "severe haemorrhaging" wow!!! never would have figured that!

 

[bewsher500]

not really interested in the semantics of the description. whether you choose to believe the existence of a shock wave and its effect.
The only way I see it is that there is more to it than the physical damage the bullet imparts on its path through an animal.

I have neck shot a deer, dropped it on the spot, bullet missed the spine by a fraction, no major arteries were severed, no significant loss of blood, yet the animal was stone dead within the time it takes to walk less than 100yds to reach it.

how did they die?
not through physical damage/tissue destruction