30 arx

[BjornF16]

In ELASTIC tissue, e.g., "flesh" and "guts," the temporary wound cavity makes no significant contribution to the terminal effects. The temporary wound cavity only makes a significant contribution in INELASTIC tissues, e.g., brain, bone, liver.

That has not been my experience with medium sized game...I've seen plenty of "mush" in elastic tissue. I'm not sure I've ever seen temporary wound cavity being an issue in bone...it just breaks, fragments or has a hole in it as a result of direct impact.

7mm Rem Mag in chest cavity of a big Axis deer is a prime example of internals being "mush"...139 GMX with 3250 fps mv; impact at ~2850 fps.

Of course, reasonable people can disagree, and there is no clear consensus. It is still being debated in military circles.

According to Col. Fackler it is the permanent cavity which represents the wound mechanism, and the wounding effects of the temporary cavity are generally exaggerated. For example, some of the human parts like lungs, blood vessels bowel walls, etc., are elastic enough and tolerate stretching. Of course, solid tissue such as liver may not be so resilient.

There is a general impression that sonic waves set up by relatively high speed bullets could kill by damaging a large number of nerves through shock. This was refuted by Col. Fackler who opined that there was no solid evidence for this conclusion as the pressure peak of about 100 atmospheres had a duration of only two microseconds. It, therefore, did not move or harm the tissues.

The real fact is that the wound size may be independent of the muzzle velocity. For example, the bullet of mid to late 19th century had the velocity of around 400 m/s (which is low by present standards), but it produced large permanent and temporary cavities as the bullet was made of lead which deformed on striking the target, thus increasing its area and capacity for tissue disruption while the high mass ensured that it retained its capacity to penetrate.

The fact is that the real parameters which one should look for in a rifle are both the mass and the velocity of the bullet -and not velocity alone at the point of impact. To quote Col Fackler, The potential for tissue disruption depends on mass and velocity realisation depends on bullet construction, shape and interaction with target tissue, the type of tissue it hits. You can't say that a certain velocity in every case will give an X amount of damage.

http://www.defencejournal.com/april98/bulletwound.htm

While not a primary wounding mechanism, the secondary effect of wounding through tissue expansion is worthy of further study as both an aid to future ammunition design and firearm forensic investigations.

http://www.brassfetcher.com/Wounding%20T...ansion.pdf

"The size and the shape of the temporary cavity depend on the amount of kinetic energy lost by the bullet in its path through the tissue, how rapidly the energy is lost, and the elasticity and cohesiveness of the tissue. The maximum volume and diameter of this cavity are many times the volume and diameter of the bullet. Maximum expansion of the cavity does not occur until some time after the bullet has passed through the target. [Emphasis added.] The temporary cavity phenomenon is significant because it has been found to be the most important factor in determining the extent of the wounding in an individual in regard to the interaction of a bullet with the body. In the case of low-velocity missiles, 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 a structure, a pistol bullet must strike that structure directly. The amount of kinetic energy lost in the tissue by a pistol bullet is insignificant to cause the remote injuries produced by a high-velocity rifle bullet.

http://kenrahn.com/JFK/Scientific_topics...speed.html