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Hydrostatic shock

4490 Views 15 Replies 11 Participants Last post by  brownie
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.

Question is, it is just a theory or does it really exist? I partook in a discussion years ago on a hunting forum. Should have seen the fireworks there.

Flame on.
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From the U.S. Dept of Justice,
Federal Bureau of Investigation,
Handgun Wounding Factors and Effectiveness,
FBI Firearms Training Unit, for law enforcement dissemination only, findings in their report dated July 14, 1989:

From the Mechanics of projectile wounding chapter:

"Temporary cavity is frequently and grossly over rated as a wounding factor when analyzing wounds.[ pertaining to all pistol calibers ]

Frequently, forensic pathologists cannot distinguish the would track caused by a hollow point bullet [ large temporary cavity ] form that caused by a solif bullet [ very small cavity ]. There may be no physical difference in the wounds. If there is not fragmentation, remote damage due to temporary cavitation may be minor even with high velocity rifle projectiles. Even those who have espoused the significance of temporary cavity agree that it is not a factor in handgun wounds.

In the case of low-velocity missle's, e.g pistol bullets, the bullet produces a direct path of destruction with very little lateral extension within the surrounding tissues. Only a small temporary cavity is produced. To cause significant injuries to structure, the pistol bullet must strike that structure directly. The amount of kinetic energy lost in tissue by a pistol bullet is insufficient to cause remote injuries produced by a high velocity rifle bullet.

The reason is that most tissue in the human body is elastic in nature. Muscle, blood vessels, lung, bowels, all are capable of substantial stretching with minimal damage. Studies have shown that the outward velocity of the tissues in which the temporary cavity forms is not more than one tenth of the velocity of the projectile. This is well within the elasticity limits of tissue such as muscle, blood vessels and lungs. Only elastic tissue like liver, or the extremely fragile tissue of the brain, would show significant damage due to temporary cavitation.

The tissue disruption caused by a handgun bullet is limited to two mechanisms. The first, or crush mechanism is the hole the bullet takes passing through the tissue. The second, or stretch mechanism is the temporary cavity formed by the tissues being driven outward in a radial direction away from the path of the bullet. Of the two, the crush mechanism, the result of penetration and permanent cavity, in the ONLY handgun wounding mechanism which damages tissue. To cause significant injuries to a structure within the body using a handgun, the bullet must penetrate the structure. Temporary cavity has not reliable wounding effect in elastic body tissue. Temporary cavitation is nothing more than a stretch of the tissues, generally no larger than 10 times the bullet diameter [ in handgun bullets ], and elastic tissues sustain little, if any, residual damage".


There you have it, verbatim from an extensive study by the feds, Hydostatic shock is not a factor in the wounding mechanism of handgun bullets.

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Thanks Brownie. Is there any report/summary you have handy that addresses high velocity rifle rounds?
Of course Ron :rolf

From the same report:

"Fragmentation occurs reliably in high velocity projectile wounds [ impact velocity in excess of 2000 feet per second ] inflicted by soft or hollow point bullets. In such a case, permanent cavity is stretched so far, so fast, that tearing and rupturing can occurr in tissues surrounding the wound channel which were weakened by fragmentation damage. It can significantly increase damage in rifle bullet wounds."

I would say not trying to resurrect an old thread but I am sooo...

Ever since I stumbled upon the Glock 33, chambered in the .357 SIG, I keep coming across this "hydrostatic shock" thing. My question is, the report that Brownie posted is almost 22 years old; do we have more current data now?

Wikipedia states this:

This was in 2009, 20 years after the FBI report.

The article further goes on to mention that police departments realize hydrostatic shock is important and they factor that in when choosing ammo.

Jim Carmichael was the shooting editor of Outdoor life magazine for 25 years and he says that hydrostatic shock is important for a more immediate disabling effect.

There is still some opposition but it looks like the recent research is leaning more towards it being a good factor. The article isn't all that long.


In addition, without having to start another thread and because it sort of fits here, what do you think about the .357 SIG cartridge? I know it's expensive but other than that?
First bolded: I've not known any police dept or any officer from numerous dept's and officers I've trained ever mention the loads they are carrying had anything to do with consideration for Hydrostatic shock. Could be a few depts may have looked at this, but it's certainly not nationwide from what I've heard [ or more appropriately, not heard ].

Second bolded: Outdoor life? They weren't discussing SD pistol calibers, that mag was about hunting and fishing.

Third bolded: From the article-------
Frank Chamberlin, a World War II trauma surgeon and ballistics researcher, also noted remote pressure wave effects.

He didn't see many pistol wounds in WW2, he saw rifle wounds, few people were shot with pistols by the enemy for him to be taken for seeing anything but rifle wounds.

In “The search for an effective police handgun,” Allen Bristow describes that police departments recognize the importance of hydrostatic shock [ HS ] when choosing ammunition

I'd like to see his sources for that statement, the people who choose pistol bullets for a dept. are unlikely to be considering HS and normally the majority have chosen what they believe to be the best compromise of bullet effectiveness and cost combined.

Fackler, also a field trauma surgeon in wartime, with lots of experience in this subject, dismisses the HS affect based on his experience. We do know that someone can fall down and die from a non fatal wound and others can be shot multiple times with little to no affect.

If I had to pick one of these theories as gospel, I’d still go along with the Hydraulic Reaction of the Body Fluids plus the reactions on the Central Nervous System.

– Col. Frank Chamberlin, M.D.

As he would have seen few handgun wounds on his table in ww2, it's probably safe to assume he believes because high velocity rifle rounds produce a HS pressure curve to surrounding tissues, that pistol bullets would do the same thing [ and they won't as they aren't traveling fast enough, at least not that they leave a permanent stretch cavity and tissue damage ].
As well, when the feds looked at HS affects based on autopsies and the data available, they found no indication pistol rounds produce HS great enough to affect an outcome. It would be hard to imagine that pistol bullets all of a sudden are producing enough HS to affect change in the body great enough to help with a stop when they haven't in the past. They aren't traveling any faster
or are any heavier today than then.

If someone wants to proffer the idea the brain suffers HS damage when an extremity is hit, I have to ask that person how ME's have never reported this phenom during their autopsies, many of which are very thoroughly explored physically. Hmm, not one ME has ever been quoted as seeing this type of HS damage in the brain or thorasic area in decades of doing GSW autopsies. If the ME's saw it often enough, there'd likely be some data from their professional org in papers written about their findings.

I'll stick with the heavy for caliber bullets at nominal speeds and not be picking any load for it's potential HS value unless there's more real research data and they can explain how they discovered something never reported on anywhere I've seen by ME's anywhere, let alone other trauma surgeons with a lifetime of living and dying patients from GSW's. :thumsup

As to the 357Sig cartridge, I own a 22 with the 357sig barrel in it. After reading all of the available data about it's capabilities of penetration and expansion vs other calibers, I decided against carrying it. It doesn't produce deeper wounds, it doesn't expand any more than other pistol rounds and come with the price of a lot more recoil than I need to be dealing with one handed in a running gun battle. Nice cartridge, I think it would be good for hunting in the heavier bullets from semi-autos but it doesn't appear to do anything other calibers can't do.
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I have a picture of someone wounded with a .223 at extremely close range.

The bullet entered and exited the thigh. The bullet did not hit the bone, but the bone was cracked all the way through in several places.

Handguns obviously do not have the same wounding capacity as high powered rifles. A .308 has the same energy at 1,000 yards that a .357 has at point blank range.
Hydrostatic shock does exist and can cause remote damage to organs. The extent depends on caliber and vicinity to the organ.
You might want to revise that bolded statement. A .223 is a .22 caliber bullet, but it creates a hell of a lot more HS than a .22 rimfire from a pistol. You could shoot a .30 caliber handgun round and not get the same HS as a .30 cal rifle round. Therefore, it's not caliber specific, it's more velocity specific. :thumsup
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