CNN's medical expert on Rep. Giffords' wounds

[Molon]

I agree that velocity is more important than energy in most parts of the body, but brain tissue is far less elastic than other soft tissue and the consequences of otherwise trivial disruption far more devastating to the victim. Likewise, the cranium is a small cavity with rigid constraints. The consequences of any energy dissipation in the head are going to be different than, say, in the chest or abdomen...again, because of the nature of the tissue, its function, and the space where it lives.

But, you could be right...I may be wrong. My opinion is based on a lecture I attended a few years ago as assistant coroner for this county and I can't lay my hands on it right now.

Your "opinion" doesn’t mean jack-shit in a technical forum. Facts are what matter here. You’re posting gun-rag BS in a technical forum about "energy" as a wounding mechanism, without posting any factual data or credible scientific references to support it. Bullets are not phaser beams and “energy transfer” is not a wounding mechanism for small arms fire. I suggest you re-educate yourself on the subject matter. You can start with the references below.


WHAT'S WRONG WITH THE WOUND BALLISTICS LITERATURE, AND WHY

by M.L. Fackler, M.D.
Letterman Army Institute of Research
Division of Military Trauma Research
Presidio of San Francisco, California 94219
Institute Report No. 239



The “Shock Wave” Myth

By Dr. Martin Fackler

Wound Ballistics Review, Winter 1991 and the Journal of Trauma, (29[10]: 1455, 1989).



Ballistic Injury

By Dr. Martin Fackler

Annals of Emergency Medicine, December 1986



Handgun Wounding Factors and Effectiveness

by Special Agent Urey W. Patrick
Firearms Training Unit
FBI Academy



....

[wrinkles]

From firearmstactiacl.com 9mm fmj.
Looks like the bullet travels about 20cm before it starts to yaw. The TC looks to start at 15cm. The TC is maybe 7cm?

[DeltaKilo]

Your "opinion" doesn’t mean jack-shit in a technical forum. Facts are what matter here. You’re posting gun-rag BS in a technical forum about "energy" as wounding mechanism, without posting any factual data or credible scientific references to support it. Bullets are not phaser beams and “energy transfer” is not a wounding mechanism for small arms fire. I suggest you re-educate yourself on the subject matter. You can start with the references below.


WHAT'S WRONG WITH THE WOUND BALLISTICS LITERATURE, AND WHY

by M.L. Fackler, M.D.
Letterman Army Institute of Research
Division of Military Trauma Research
Presidio of San Francisco, California 94219
Institute Report No. 239



The “Shock Wave” Myth

By Dr. Martin Fackler

Wound Ballistics Review, Winter 1991 and the Journal of Trauma, (29[10]: 1455, 1989).



Ballistic Injury

By Dr. Martin Fackler

Annals of Emergency Medicine, December 1986



Handgun Wounding Factors and Effectiveness

by Special Agent Urey W. Patrick
Firearms Training Unit
FBI Academy



....

Excuse my ignorance, but if the bullet will tend to crush and obliterate tissue, as well as force tissue out of its path by virtue of the fact that it MUST displace tissue, would this not cause compression of brain matter? And under such compression in an organ that is relatively inelastic, would the tissue then not be suffering from greater damage by the act of compression in the vicinity of the permanent cavity, as well as the damage done directly in creating the permanent cavity?

Therfore, would it not be true to state that the amount of damage caused by the bullet traversing through a length of the brain would in fact be greater than a bullet that traversed some distance in and stopped as it would not continue on a path causing damage?

Also, would not the existence of two holes in the cranial cavity compared with one be also a mitigating factor to further damage caused by any swelling that may occur due to blood flow, as there exists points where the blood may be readily drained off and prevent further tissue damage?

[wrinkles]

I agree that velocity is more important than energy in most parts of the body, but brain tissue is far less elastic than other soft tissue and the consequences of otherwise trivial disruption far more devastating to the victim. Likewise, the cranium is a small cavity with rigid constraints. The consequences of any energy dissipation in the head are going to be different than, say, in the chest or abdomen...again, because of the nature of the tissue, its function, and the space where it lives.

But, you could be right...I may be wrong. My opinion is based on a lecture I attended a few years ago as assistant coroner for this county and I can't lay my hands on it right now.

The TC is created by velocity not energy dissipation. Yes from what I read inelastic tissue is damaged by the TC more than elastic tissue.



"The Wound Profile: A Visual Method for Quantifying Gunshot Wound Components." Martin L. Fackler, M.D., and John A. Malinowski, B.S., JTrauma

The erroneous assumption that the ammount of kinetic energy "depostited" by a projectile is a measure of the damage it produces continues to misslead.

Wounds that result from the same ammount of "kinetic energy deposit" can differ widely, depending on the predominant tissue
disruption mechanism (crush or stretch) and the anatomic location of the desruption.

[bernieb90]

The TC is created by velocity not energy dissipation. Yes from what I read inelastic tissue is damaged by the TC more than elastic tissue.

There seems to a be a lot of confusion as to how exactly kinetic energy figures into wound creation. Kinetic energy of a projectile alone is a poor measurement of wounding effectiveness, not because it is irrelevant, but because there is no information as to how this energy is used to create the wound. Bullets with the same Kinetic energy can behave very differently depending on construction, weight, and diameter.

Per Macpherson the projectiles kinetic energy is in fact lost in soft tissue in a number of ways. Temporary cavity creation (conversion of kinetic to potential energy ie. stretching a rubber band), bullet deformation, heat generation (any time material is deformed or stretched it generates heat), and cutting the tissue ulimately all of the kinetic energy of the projectile is in fact mechanically dissipated as heat. All things being equal temporary cavity size will in fact be proportional to the rate of kinetic energy transfer to the tissue. This is why temporary cavity increases as the bullet expands or yaws (which causes it to slow more rapidly). If we only look at velocity we loose this very important aspect of physics. The brakes on your car do the same thing. They convert the kinetic energy of your vehicle to thermal energy. If you double your speed it is 4 times harder to stop the car not twice, as hard.

If we look at the now infamous gelatin photo comparing service calibers we can clearly see this effect.



The 125gr .357 Sig, and 124gr load penetrate to almost identical depth with nearly identical expanded diameters. The temporary cavity created by the .357 Sig is clearly larger. Didipating a greater ammount of energy over the same distance without bullet fragmentation results in a higher energy transfer rate to the tissue, and a larger temporary cavity. Again throw a rock harder at a pond, and you get a bigger splash.

Here is the part that gets everyone worked up. Temporary cavity size alone does not tell us how severe the wound will be unless we are dealing with inelastic tissue. Because most of the tissue in the body is elastic it tells us almost nothing about wound severity, and we look to expanded diameter, or fragmentation effect to determine the degree of damage done by crushing, or tearing, of tissue.

Since handguns normally do not produce temporary cavities large enough to exceed the elastic limit of most human tissue, and do not fragment in a manner that aids wounding we do not look at temporary cavity in handgun wounds as a contributing factor.

[Molon]

Excuse my ignorance. . .

WTF are you babbling about? Nothing that you stated has anything to do with the subject of the myth of "energy transfer" as a wounding mechanism. Did you even read the references that I posted that you quoted me on?



....

[wrinkles]

OK TC is created by velocity and energy.

The argument is that doesn't if the same identical bullet shape traveling at the same speed (same kinetic energy).

1. Traverse the cranium and exit.

2. Stop inside the cranium.


Bullet 2 would cause more damage because it "deposited" all it's energy in the cranium. I Don't believe it would.

Bullet 1 would do more damage because it created a longer (larger) wound channel. Yes because it creates a larger wound.

By that I mean, if the bullet can create a hole all the way through the target it will case more damage than if it were to stop 1/2 or 3/4 of the way through.

[bernieb90]

Without knowing why the bullet stopped in the cranium, and what kind of damage it dis there is no way to tell which wound would be more severe based on only that information. A .240gr bullet from .44 magnum that passes through the skull will clearly do more damage than a .22 LR that does not. When we talk about specific calibers, and particular loads we have to be careful to be very specific.

Without a doubt a JHP 9mm that expands, but does not exit the skull would do more damage than a 9mm FMJ that exits assuming that the 2 projectiles follow the same path. However if we look at two identical projectiles fired from the same weapon where one exits, and one does not, and the wound track was identical then we must assume that the exit wound adds additional trauma. Bullet penetration depth depends on a lot of factors. Sometimes bullets deflect of things they should easily penetrate, or they simply fail to penetrate all together. A blanket statement that an exit wound means less severe trauma is not always correct, although there are some instances where it may be.

[[SAS]Reaver]

pistol projectile lack the velocities needed to achieve permanent cavity.

[wrinkles]

Without knowing why the bullet stopped in the cranium, and what kind of damage it dis there is no way to tell which wound would be more severe based on only that information. A .240gr bullet from .44 magnum that passes through the skull will clearly do more damage than a .22 LR that does not. When we talk about specific calibers, and particular loads we have to be careful to be very specific.

Without a doubt a JHP 9mm that expands, but does not exit the skull would do more damage than a 9mm FMJ that exits assuming that the 2 projectiles follow the same path. However if we look at two identical projectiles fired from the same weapon where one exits, and one does not, and the wound track was identical then we must assume that the exit wound adds additional trauma. Bullet penetration depth depends on a lot of factors. Sometimes bullets deflect of things they should easily penetrate, or they simply fail to penetrate all together. A blanket statement that an exit wound means less severe trauma is not always correct, although there are some instances where it may be.

Agreed.

Here's what I was commenting on:

If the bullet stops in the body, whether cranium or anywhere else, that tells us that all of its energy has been expended in creating the wound components (TC and CC). If it exits the body, that means that it expended at least some energy outside the body after it exited.

It's not about expending all it's energy in the target. It's about the wound channel.