Bullet Pressure Wave Effects On Incapacitation Time
BY Herschel Smith
5 years, 6 months ago
Reader =BCE56= links Ballistic Pressure Wave Contributions To Rapid Incapacitation In The Strasbourg Goat Tests.
Chamberlin observed damage remote from the wound channel he ascribed to the hydraulic reaction of body fluids [CHA66]. Tikka et al. showed that ballistic pressure waves originating in the thigh reach the abdomen. Wounding and delayed recovery of peripheral nerves have been reported [LDL45, PGM46]. Pressure waves cause compound action potentials in peripheral nerves [WES82], and ballistic pressure waves have been shown capable of breaking bones [MYR88].
This shows that, all other factors being equal, bullets that produce pressure waves of greater magnitude incapacitate more rapidly than bullets that produce smaller pressure waves. The Strasbourg test data convincingly supports the pressure wave hypothesis and allows (perhaps for the first time) the fast response time to be modeled as a function of peak pressure wave magnitude.
[ … ]
The trend in bullet design over the last decade has drifted toward bullets with little fragmentation and a higher percentage of retained mass. Bullets that both fragment and meet minimum penetration requirements create larger pressure wave magnitudes and offer improved incapacitation potential.
There is much more at the link. I find it especially interesting that the authors use a 4*pi()*r^2 model for pressure wave solid angle (as with sound, light and radiation, unattenuated [or scattered] and unreflected). The pressure wave isn’t forward peaked.
I often claim I have the best readers on the internet. I really mean it. This is a good example of that.
And this analysis goes to the heart of the design of the 5.56mm round, which is to induce a pressure wave due to high velocity (KE = 1/2 * m * v^2) and then fragment into shrapnel with multiple wound tracks.
Thanks to reader =BCE56= for that great read.
On May 16, 2019 at 12:06 am, BRVTVS said:
I also find it odd that the pressure wave isn’t forward peaked. Instinctively, I’d expect a hemisphere area (2*pi*r**2) to provide a better estimate. That said, the least squares fit to find p_o eliminates and practical consequence of that oversight.
On May 16, 2019 at 12:07 am, BRVTVS said:
Sorry, my last sentence should read, “the least squares fit to find p_o eliminates any practical consequence of that oversight.”
On May 16, 2019 at 8:50 am, Matt Bracken said:
A lot of very knowledgeable Vietnam vets swear by the M-16A1 launching the 55grain M-193 at a full 3,250 fps. They say this was Stoner’s intent, and that shortening the barrels and firing larger projectiles at less fps has diminished the capability of the platform/projectile combination.
It’s often said that the M-855 62 grain green-tips were introduced with the M-16A2 to pass a NATO test for penetrating a Soviet helmet of that era at long range. This was a “pass-fail” requirement for retaining the 5.56mm as a NATO round. However, while great at making holes at long range, the M-855 does much less damage to human bodies at close range.
I’m no expert, but this is what I always heard. YMMV, I submit this comment only for discussion.
On May 16, 2019 at 3:32 pm, =BCE56= said:
Thanks for the HT.
What struck me about this study was the incapacitation times (rather than the theoretical basis as to why they differ.)
There are numerous accounts of individuals absorbing multiple center-mass torso hits that ultimately proved fatal who were able to return fire.
Under certain circumstances, ten seconds can be a very long time…
=TW=
On May 16, 2019 at 4:50 pm, 41mag said:
Love the physics but I prefer just a bigger hole.
On May 18, 2019 at 5:27 am, Dan said:
While there is science behind what happens to tissue struck by bullets there is a saying that while originally made regarding fetuses and newborn infants it also applies in other venues. When asked a question regarding why a specific event did not occur during a pregnancy even though all the
textbooks said that it was normal my mother….an old and wise 85 years of age simply said “the baby never read that textbook”….meaning that just because science says a human body should do something doesn’t mean it always does. The same can be said for the effects of gun shot wounds. Each body reacts uniquely to the trauma. So while statistics can indicate the probability of the outcome it can’t guarantee that outcome.