Saturday, May 23, 2009

The “myth” of stopping power.

Anonymous said...
From the FBI Firearms Training Unit:

"Barring a hit to the brain, the only way to force incapacitation is to cause sufficient blood loss that the subject can no longer function, and that takes time. Even if the heart is instantly destroyed, there is sufficient oxygen in the brain to support full and complete voluntary action for 10-15 seconds.
Kinetic energy does not wound. Temporary cavity does not wound. The much discussed "shock"
of bullet impact is a fable and "knock down" power is a myth. The critical element is penetration. The
bullet must pass through the large, blood bearing organs ..."

And yet people have been shot in the brain on occasions and still didn’t loose consciousness and survived. So that pretty much ruins that affirmation. Unless a very fast rifle round with a center of the head hit or a hollow point projectile turn the brain to pulp, there's no 100% assurance that a head shot will stop an attacker immeditaly for sure. Again, it still defends on where it hit precisely and with what caliber.

Here’s my offer, let me hit you once in the face, chest, stomach, or even a good kick to the thigh.
If you are still standing we can discuss the “myths” of kinetic energy some more. :^)
If as you say temporary cavity has no implication, there would be no difference between 38 special, 9mm and 45 ACP, all with round nose ammunition, since the permanent cavity is almost the same in all three in spite of the slight difference. Yet 45 hardball is clearly a superior stopper, based on street results.
That information is dated and it is abundantly proved wrong by empiric evidence. As I mentioned, a shoulder shot putting an attacker down for good, a gut shot with a .32 long dropping an attacker armed with a knife instantly, shock by 12 ga. LTL plastic pellets shot at contact range, even without serious penetration the shock was enough to leave the soccer player unconscious on the ground instantly. Trauma kills, kills all the time.

Seriously people, we can debate until the end of time, but some things are not opened up for debate:
1)Not all calibers are equal
2)Some have better one shot stop rates than others
3)Not looking into those rates and taking them into consideration is a pretty stupid idea.



Blackeagle said...

FerFAL, I hate to say it, but you're in the wrong on this one. The FBI Handgun Wounding Factors report is still the best source on the terminal ballistics effects of pistol bullets. The "one shot stop rates" that you reference are the product of some truly atrocious statistical mangling and aren't worth the paper they're written on.

A pistol round is like a long range drill: it bores holes in targets. The key is to put those holes in the right places, either destroy a vital part of the central nervous system (the brain stem or upper spinal cord) or destroying the heart or major blood vessels and waiting for them to bleed out. Shock and temporary cavity are not relevant. Energy is relevant only as far as it allows the bullet to reach and destroy those vital areas.

Now I do agree that a .45 is more effective than a 9mm or .40, but this has nothing to do with energy or shock or temporary cavity. It's because heavier bullets are less likely to be deflected by bone, making them more likely to penetrate and get to those vital areas.

Finally, telling someone, "Usually one center of mass shot is all it takes" with any firearm, regardless of caliber, is downright irresponsible. A couple of years ago a physician lecturing on terminal ballistics at the annual Polite Society conference was asked, "what should I expect an attackers immediate response to be if I double tap them in the heart with a .45?" His response was, "nothing". Even with the heart totally destroyed and absolutely no blood pressure, the body's tissues contain enough oxygen to continue to act for another 10-15 seconds. Expecting a "one shot stop" with any firearm is a recipe for disaster if you are attacked and that expectation is not met. People need to be trained to shoot criminal assailants repeatedly until they are no longer a threat.

FerFAL said...

Blackeagle, don’t hate it, we can disagree sometimes. :)
Would be very boring otherwise.

Shooting with anything you have to be ready to keep shooting until the other guy goes down, but there’s still statistics and differences between calibers.
Take 357 SIG for example. When I mentioned it, I also mentioned a police department that had been having great results with it, and they stated that in most cases one shoot was all it took.
This shouldn’t interfere with training and shooting until the bad guy goes down, but I at least consider it an interesting fact that in most cases, one shoot was all it took, similar to the trusted 124gr 357 magnum round.
If we didn’t take these things into account, we’d all be carrying 22 LR autos.
But when you look into the real world fact, you have people getting shot several times in the head with a 22 LR and still keep coming, while there are cases of people getting shot in the head with 357 magnum hollow points, and the shock wave was so great, it actually pushed the eye globe out of the socket, of course destroying the brain with the hydraulic shock it created in the soft brain tissue, stopping cerebral activity instantly.
Calibers are not all equal and some are more efficient than others. Within a margin of error, I consider it valuable info to analyze those cases and come with approximate statistics.
If shock and temporary cavity wheren't relevant, a round like 7,62x51 would be practically useless, when in relaity it does the job quite well... better tha 5,56 that creater a larger permanent cavity.. but a much smaller temporary cavity.


Anonymous said...


"Past Performance Does Not Guarantee Future Success"

Anonymous said...

The .45 enjoys a cult following, but it's a myth that it's a superior stopper. With comparable, modern, bonded-core bullets, there is not much of a statistical difference between any of the practical defensive handgun calibers. They all deliver about the same amount of energy as a thrown baseball. They all have spectacular one-shot stops, and they all have spectacular failures to stop. Bigger bullets do cause more damage. However, handgun bullets aren't very big. Accuracy can make up for power but not vice-versa. Unfortunately, accurate shots are extremely difficult in dynamic defense scenarios. Think of your opponent as a bag of blood, and your job is to empty the bag.

Anonymous said...

Also, comparing pistol calibers with rifle calibers is apples to oranges. At velocities above about 2,000 FPS, there is indeed significant tissue damage due to shock and the stretching of the temporary cavity. None of the typical, practical defensive handgun calibers reach those velocities, however. With 9mm, 40 S&W, .357 Sig, .357 Magnum, and .45's, the permanent cavity is what counts.

Blackeagle said...

"If shock and temporary cavity wheren't relevant, a round like 7,62x51 would be practically useless, when in relaity it does the job quite well."

Rifle rounds are a very different animal from pistol bullets. There's a velocity threshold somewhere around 2000 feet per second, beyond which temporary cavity does become significant. At those speeds, the round is traveling fast enough that the temporary cavity expands fast enough to actually tear most types of tissue.

These sorts of dynamics don't apply to pistol bullets. They just don't have the necessary velocity.

Bones said...

In a self defense situation your job is to survive the encounter. In most cases just showing the gun to the bad guy will be enough to deter him. Running away may be your best option.

Scientific studies definitively proving one gun/caliber/bullet type/wounding factor is best do not exist and for every rule there is an exception. The effect of shooting a person is unpredictable.

Pay attention to what the cops are saying since they're the ones that use guns on the street most often.
Unfortunately all we really have are anecdotes, opinions & probabilities.

You have to pick a gun you can carry and shoot well. It should hold as many rounds as possible because you will probably miss and one hit might not stop the bad guy. Get a good brand of expanding HP. Physics tells us that bigger and hotter rounds are better so long as you can handle them well. Practice enough so you can use the gun automatically. Finally, do everything in your power to avoid ever actually needing the gun.

Anonymous said...

Considering you will be shooting someone with your high cap automatic alot of times (like till you run out of bullets) and moving at the same time.
'One shot stop' statistics or even gelatin results are even more useless.

I would go for reliability and amount of bullets, just like ferfal says. Luckily all the quality high cap autos don't go below 9mm in calibre.

PKS said...

The problem with the "one-shot stop rates" is, as others have mentioned, is that the statistical basis of those figures is shaky at best.

Which is not something that anyone can do much about, given that we're not able take a random sampling of the population, and compare the effects of shooting them with various calibers.

I mean, ok, sure, everything else being equal, better a bigger hole than a smaller hole. But shot placement matters more than caliber.

David said...

FWIW, even hits with 7.62x51 gain substantial terminal effect by using OTM or hunting-type bullets intended to expand.

Analyses of shootings where someone kept on fighting even after sustaining significant damage appear to support the notion that motivated people don't stop until the brain or upper spine are at least rattled pretty hard.

With low vel ammo like pistol rounds, this means the bullet or a piece of it has to actually hit one of these structures, hence the call for adequate penetration. Paradoxically, adding velocity to JHPs often makes them penetrate less (9x19 vs 9x23 are an example).

High vel rounds do appear to buffet the upper spine if the temporary cavity occurs close enough to it. This means shot placement is apparently not quite as critical, and explains why hunters discuss the concept of DRT (Dead Right There). Dropping the animal in its tracks is not about shock. It's about a physical shock wave buffeting the upper spine. This is why hunters generally use expanding bullets which have a much larger temp and permanent cavities, and why hyper-fragmenting bullets are absolutely avoided for big game (due to inadequate penetration).