shock wave?

galamb · Jul 30, 2014

roundball said:
BrownBear said:

"...it's clear that lots more is going on with the bigger balls, lower velocity or not..."

Click to expand...

Whompability.

What many archers would recognize as "slug force".

That is why a relatively slow moving (maybe 180 fps) arrow weighing 525 grains, with a massive impact force of "maybe" 45 foot pounds will travel all the way through an animal.

It is the "momentum" of that slow moving, heavy arrow that "refuses" to slow down.

While the blades on the broadhead ease the way, greatly lowering the impact/penetration resistance, compared to say a roundball, it is momentum that is often overlooked with black powder arms (because they are always compared back to CF arms where velocity and Kinetic Energy are the gold standards when determining viability for specific game).

When relying on slug force for penetration, it's desirable to maintain (forward) momentum as long as possible, with the actual impact force being "almost" a non-issue (of course, impact force must be sufficient to initially penetrate).

When a projectile impacts the hide/skin of an animal at say 1000 fps the "resistance" to penetration can be described as "X" resistance.

Now if that exact same projectile impacts at twice the speed (so 2000 fps in this example) the resistance to penetration is NOT 2X it is 4X - doubling impact speed "quadruples" the resistance to penetration.

(and once the skin is penetrated there is obviously further resistance - less going through soft tissue, more with muscle and ever more it you hit bone)

So in calibers 58 and greater (in particular), despite their "lower" impact velocity, that very factor results in them meeting "less resistance" than if they were traveling faster PLUS, because of their "weight" (being considerably greater than smaller BP calibers or even high speed CF rounds), their "retained" slug force is greater because they were slowed down less by impact and their weight keeps driving them forward.

(try to stop a train in the same distance as a mini-van even if the train is only going half the speed of the van).

The result is "more retained energy", on a percentage basis even compared to a high powered CF projectile.

(not to be confused with "more" energy, but more "retained energy" - and the better energy is retained, the deeper the penetration, all else being equal)

The job of the Black Powder hunter is to find the caliber/load/range where their "choice" will completely pass through the animal they are shooting.

(for anyone wanting to read more on slug force and penetration studies on actual animals, google Dr. Ed Ashby + penetration - he was an ER Doc that specialized in gunshot wounds on people and undertook significant studies on game animals since he was also an avid bowhunter)

roundball · Jul 30, 2014

A very simple analogy:

Little kid barely able to get a heavy bowling ball started down an alley...but if it stays out of the gutter and finally reaches the pins, it continues to plow right on into them.

longcruise · Jul 30, 2014

for anyone wanting to read more on slug force and penetration studies on actual animals, google Dr. Ed Ashby + penetration - he was an ER Doc that specialized in gunshot wounds on people and undertook significant studies on game animals since he was also an avid bowhunter)

Hope he didn't work on too many people! Wasn't he a veterinarian?

galamb · Jul 30, 2014

Don't think so. He was a career "military" physician and then later consulted/worked for the government.

"In 1994 he retired from the U.S. Public Health Service and moved to Africa to enjoy the continent's spectacular hunting"

During the 80's he did a number of studies on animals in Africa, but he was certainly NOT a Veterinarian - but he WAS "Military Vet"

AZbpBurner · Jul 30, 2014

Loyalist Dave said:
Tell me again why we believe hydrostatic shock has nothing to do with the killing power of round balls from muzzleloaders....?

Click to expand...

Because mamals are not milk jugs.

With the milk jug you are talking about one large chamber of nothing but liquid... when you are talking about mamals you have layers of tissues of various densities with connecting tissues that alter how the wave (if formed) moves through the target, and what amount of damage, if any, is sustained. Internal tissues have some elastic qualities. Thus you don't get a very reliable result until the impact velocity is as mentioned, at 2500 fps or higher.

LD

So, you're leaving the 'family restaurant', when an unruly drunk accosts you wielding a big knife. He means to do you harm, and won't be dissuaded. He's also tanked up on about 4 pitchers of beer.

When you shoot him dead center, will hydrostatic pressure from the liquid-filled stomach explode, causing his head to detach and sail 15' into the air?

azmntman · Jul 30, 2014

Hoping for video on this scenario :grin:

nkbj · Jul 30, 2014

AZbpBurner said:
Loyalist Dave said:

Tell me again why we believe hydrostatic shock has nothing to do with the killing power of round balls from muzzleloaders....?

Click to expand...

Because mamals are not milk jugs.

With the milk jug you are talking about one large chamber of nothing but liquid... when you are talking about mamals you have layers of tissues of various densities with connecting tissues that alter how the wave (if formed) moves through the target, and what amount of damage, if any, is sustained. Internal tissues have some elastic qualities. Thus you don't get a very reliable result until the impact velocity is as mentioned, at 2500 fps or higher.

LD

Click to expand...

So, you're leaving the 'family restaurant', when an unruly drunk accosts you wielding a big knife. He means to do you harm, and won't be dissuaded. He's also tanked up on about 4 pitchers of beer.

When you shoot him dead center, will hydrostatic pressure from the liquid-filled stomach explode, causing his head to detach and sail 15' into the air?

If he wasn't drinking Lite and you had enough whompability then you got a purty good shot at it!

Jason Lewis · Jul 31, 2014

for those of you who may be interested in wound ballistics, google dr. martin fackler. founder of the international wound ballistics association. dr. fackler has done most of the pioneering research into the field and has an extensive amount of experience based on his medical service during vietnam. with some digging you can find many of his articles and ballistic gel tests. however i can briefly sum up some of the research. mammals contain two types of internal organs, solid organs i.e. liver and hollow organs which can contain either air, or fluid. "hydrostatic shock" which is an old term coined in the early 20th century by gunwriters hunting with the then new high powered rifles to describe why animals seemed to drop right where they were standing when struck by a bullet. today we call that cavitation. the two types of organs react very differently to the passage of the bullet and resulting pressure waves created, solid organs expand and then do not retract creating a very severe wound channel. while hollow organs filled with air, tend to be elastic and snap back into posistion and have less damage. this was first seen with 5.56 nato rounds from m16 wounds. fluid filled organs generally erupt when struck directly and leak if struck indirectly. (we've all seen whats left after a heart shot) however, the vascular system behaves differently, it tends to conduct the pressure waves through out the body, if the cavitation is severe enough, it causes the capillary system in the brain and spinal cord to rupture which basically means the mammal struck with a bullet moving faster than 2500fps, has a stoke and falls right where it was standing.

this was tested on livestock, pigs if i recall correctly. they implanted pressure sensors in the pigs skull and then fired at the pigs in different places, i.e. the chest, hind legs etc. what was discovered was that even when poorly struck in the hind leg, there was still a remarkable increase in the intracranial pressure and upon dissection it was noted that there was some bleeding in the brain tissue.

and yes, more than just velocity plays into the amount of cavitation created. a large enough projectile does not need a large amount of speed to create cavitation. our round balls/bullets are plenty big enough and fast enough to cause it.

just my two cents. it's fascinating stuff to me, but i kinda have to know it.

Loyalist Dave · Jul 31, 2014

Spence if you are hunting and eating milk jugs, or if they are attack you, then the actual scientific data collected over the past four decades obviously doesn't apply.

LD

nkbj · Jul 31, 2014

Yep, "hydrostatic" means there is a constant and unchanging hydraulically applied pressure and is completely wrong as a term applied to the reaction to the passage of a bullet through anything. People have noted that in the past but the term is set in the vernacular like a tick in a dog's ear.
With black powder velocities the rate of displacement (volume over time) generally describes the observed destructiveness in flesh. How to assure that adequate penetration is achieved is a separate consideration and gives that trade off in diameter versus velocity.
Say, anybody developed that .58 load with 2000FPS yet?
:haha:

Loyalist Dave · Jul 31, 2014

When you shoot him dead center, will hydrostatic pressure from the liquid-filled stomach explode, causing his head to detach and sail 15' into the air?

Well ignoring the obvious fact that the stomach has an entire esophogus, and has two very weak sphincters, PLUS ignoring the fact that the stomach also produces gas at the same time which would compress....OH and ignoring the fact that the stomach stretches, and a drunk with a distended stomach so stretched it could not expand would not be doing anything but yelling for an ambulance....

IF you filled the guys stomach with water, then sewed both openings closed... THEN froze the the stomach wall so it would not stretch, THEN when struck buy a bullet the stomach would probably shred... of course due to the space inside the thoracic cavity, it would not cause the head to explode...,

What exactly was the point you were trying to make? :rotf:

Folks you seem to think I'm voicing my opinion. I'm not disputing what happens to milk jugs... and all that I can do is present what the guys with the MD's and PhD's have found through experimentation, documentation, and observation and have concluded happens to people and large game when either are struck with a bullet.

You can complain about it all you want, but unless you get the PhD, or you cite some credible source with credible methods that debunks the MD's and PhD's and their conclusions, then the objections based on argument not experiment are moot, for if it isn't tested then it's sophistry not science.

LD

George · Jul 31, 2014

Well, my question was based on idle curiosity, never intended to debunk any MDs or PhDs, bless their pointy little heads. I've had a fair amount of experience with gunshot wounds in large animals and no small amount in humans, so I at least have a good basis for the curiosity.

Something caused my jugs to explode when I shot them using my hunting load. Whatever that was, it would be present if I shot a deer with that load. Until a better explanation comes along, I'll assume what I saw at low velocity was just a small amount of what happens with very high velocity. A matter of different degrees of the same thing.

Spence

Rifleman1776 · Jul 31, 2014

I think all this talk :yakyak: is causing enough shock to kill anything that comes close. :shocked2: :rotf:

OK, my tuppence. I once read a lengthy study (book size) report done by the FBI on this subject. The study was done by shooting sheep, dead and alive, with various handguns to determine effectiveness of bullet design, velocity, etc. After many-many rounds of shooting and an equal number of unfortunate sheep, they concluded almost nothing. All the study showed with certainty is that precisely duplicating the effects of one shot from the next is impossible. Yes, cavitation, hydrostatic shock, penetration, etc. were all evaluated but to answer why one sheep (or man) might drop instantly and another might keep coming from seemingly identical hits was never answered.
And, that is why we all agree on the same mantra: "placement, placement, placement"

Billnpatti · Jul 31, 2014

AMEN!!! :thumbsup:

longcruise · Jul 31, 2014

I see that now. A Google search brought it straight up.

Not sure how I missed that. Have read everything he has written on arrow penetration.

crockett · Jul 31, 2014

Medic302: you stated it in terms beyond my knowledge but that was basically my understanding, that all projectiles will cause hydrostatic shock but the issue is whether the level is so bad as to cause permanent tissue destruction or whether the tissue can "spring back" from this impact. I never knew about there being different organs that react differently. In any event, when the small caliber, high velocity cartridges were developed people were amazed at the tissue damage so what we might be seeing on the milk jugs is damage that on an animal, the animal might have been able to "spring back from" at least in part. Just sort of wondering about it all.

TFoley · Jul 31, 2014

George said:
I'll be glad to see the performance of a .54. I've seen the videos posted by duelist1954 and others, but I believe those were done with pistols/revolvers.Spence

I'm much more interested in that beautiful rifle than learning any more about a phenomenum that I already have far too much experience in seeing at first hand.

tac

Col. Batguano · Jul 31, 2014

Loyalist Dave said:
When you shoot him dead center, will hydrostatic pressure from the liquid-filled stomach explode, causing his head to detach and sail 15' into the air?

Click to expand...

Ya gotta love the deductive simplicity of cartoon physics, don't you? :grin:

Dean2 · Jul 31, 2014

Medic302 said:
for those of you who may be interested in wound ballistics, google dr. martin fackler. founder of the international wound ballistics association. dr. fackler has done most of the pioneering research into the field and has an extensive amount of experience based on his medical service during vietnam. with some digging you can find many of his articles and ballistic gel tests. however i can briefly sum up some of the research. mammals contain two types of internal organs, solid organs i.e. liver and hollow organs which can contain either air, or fluid. "hydrostatic shock" which is an old term coined in the early 20th century by gunwriters hunting with the then new high powered rifles to describe why animals seemed to drop right where they were standing when struck by a bullet. today we call that cavitation. the two types of organs react very differently to the passage of the bullet and resulting pressure waves created, solid organs expand and then do not retract creating a very severe wound channel. while hollow organs filled with air, tend to be elastic and snap back into posistion and have less damage. this was first seen with 5.56 nato rounds from m16 wounds. fluid filled organs generally erupt when struck directly and leak if struck indirectly. (we've all seen whats left after a heart shot) however, the vascular system behaves differently, it tends to conduct the pressure waves through out the body, if the cavitation is severe enough, it causes the capillary system in the brain and spinal cord to rupture which basically means the mammal struck with a bullet moving faster than 2500fps, has a stoke and falls right where it was standing.

this was tested on livestock, pigs if i recall correctly. they implanted pressure sensors in the pigs skull and then fired at the pigs in different places, i.e. the chest, hind legs etc. what was discovered was that even when poorly struck in the hind leg, there was still a remarkable increase in the intracranial pressure and upon dissection it was noted that there was some bleeding in the brain tissue.

and yes, more than just velocity plays into the amount of cavitation created. a large enough projectile does not need a large amount of speed to create cavitation. our round balls/bullets are plenty big enough and fast enough to cause it.

just my two cents. it's fascinating stuff to me, but i kinda have to know it.

Very good [post. I would also refer people to PO Ackley's volume II. It contains a very good dissertation on extensive live animal tests carried on over a number of years re gunshot wounds done by the U.S. Army's Colonel Frank T Chamberlain. They were testing a series of existing military calibers and a number of proposed ones. It very clearly lays out the effects of hydrostatic or cavitation shock. It also pointed out how utterly amazing light weight, well constructed small caliber bullets travelling 4000 fps killed due to the shock effect.

longcruise · Jul 31, 2014

It very clearly lays out the effects of hydrostatic or cavitation shock. It also pointed out how utterly amazing light weight, well constructed small caliber bullets travelling 4000 fps killed due to the shock effect.

I think bullet construction is one of those things that can result in a lot of variation in the cavitation effect. The difference in cavitation between an FMJ and an identical bullet designed to disrupt dramatically will be considerable.

OTOH, we don't see such a dramatic difference in projectile upset with our round balls. A faster one will flatten out some on impact whereas a slower one will better retain shape. Seems like either way if there is adequate penetration of vital organs with an adequate sized ball the job pretty much gets done.

shock wave?

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