The truth about handgun knockdown power

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Marcus L.

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Here's a good article from PoliceOne that is informative and refreshing.



From PoliceOne

11/19/2008

P1 Exclusive: The truth about handgun knockdown power
By Commander Jeffry L. Johnson
Long Beach Police Dept., Detective Division
Special contributor to PoliceOne

There is undoubtedly no other myth more perpetuated and closely held (even now) by many law enforcement professionals than what I have previously referred to as the “Demonstrative Bullet Fallacy,” or in plainer terms, the idea that any handgun of any caliber has “knockdown power,” in that the sheer size and force of the bullet can knock a person down. Closely related is the myth that bullet size — rather than shot placement — can determine or ensure a “one shot stop.” Both are inaccurate, unscientific, and dangerous, and have no place in the training of law enforcement professionals.
Not that any of this is new information. This fact has been generally known for about six hundred years or so. Notable intellects such as DaVinci, Galileo, Newton, Francis Bacon, and Leonard Euler all studied physics and ballistics, as did many others. It was Newton’s research that led Benjamin Robbins to invent the ballistic pendulum in 1740 (the first device to measure bullet velocity).
There is no mystery here — the truth has been documented time and again. So how is it that we still don’t get it? One word: Hollywood.
Ever since Dirty Harry came along with his .44 Magnum hand-cannon, when someone gets shot in the movies or on TV (and don’t forget video games) two things happen: 1) the victim is thrown back convulsively, through windows, off balconies, etc. and 2) there will immediately emerge a geyser of blood spewing forth from the wound, leaving no doubt that this person has been shot, and pinpointing exactly where the bullet has struck.
Many firearm and shooting magazines picked up on the idea as well, discussing and propagating the pseudo-scientific idea of handgun “knockdown power” and “one shot stopping power.”
The Truth
The Federal Bureau of Investigation Firearms Training Unit published a concise yet insightful report that speaks directly to this issue of firearm wounding ballistics and the misconceptions that have surrounded this area.
These so called [knockdown power] studies are further promoted as being somehow better and more valid than the work being done by trained researchers, surgeons and forensic labs. They disparage laboratory stuff, claiming that the “street” is the real laboratory and their collection of results from the street is the real measure of caliber effectiveness, as interpreted by them, of course. Yet their data from the street is collected haphazardly, lacking scientific method and controls, with no noticeable attempt to verify the less than reliable accounts of the participants with actual investigative or forensic reports. Cases are subjectively selected (how many are not included because they do not fit the assumptions made?). The numbers of cases cited are statistically meaningless, and the underlying assumptions upon which the collection of information and its interpretation are based are themselves based on myths such as knockdown power, energy transfer, hydrostatic shock, or the temporary cavity methodology of flawed work such as RII. (1)

The truth is, the whole idea of handgun knockdown power is a myth. It simply doesn’t work that way. The FBI report further clarifies:
A bullet simply cannot knock a man down. If it had the energy to do so, then equal energy would be applied against the shooter and he too would be knocked down. This is simple physics, and has been known for hundreds of years. The amount of energy deposited in the body by a bullet is approximately equivalent to being hit with a baseball. Tissue damage is the only physical link to incapacitation within the desired time frame, i.e., instantaneously. (2)

The report cites previous studies that have calculated bullet velocities and impact power, concluding that the “stopping power” of a 9mm bullet at muzzle velocity is equal to a one-pound weight being dropped from the height of six feet. A .45 ACP (45 auto) bullet impact would equal that same object dropped from 11.4 feet. That is a far cry from what Hollywood would have us believe, and actually flies in the face of what even many in law enforcement have come to mistakenly believe.
The FBI report also emphasizes that unless the bullet destroys or damages the central nervous system (i.e., brain or upper spinal cord), incapacitation of the subject can take a long time, seemingly longer if one is engaged in a firefight.
Failing a hit to the central nervous system, massive bleeding from holes in the heart or major blood vessels of the torso, causing circulatory collapse is the only other way to force incapacitation upon an adversary, and this takes time. For example, there is sufficient oxygen within the brain to support full, voluntary action for 10-15 seconds after the heart has been destroyed. (3)
More often than not, an officer firing at a suspect will not immediately know if he or she has even struck the target. The physics are such that the body will rarely involuntarily move or jerk, and usually there is no noticeable spewing of blood or surface tearing of tissue. Often there is no blood whatsoever. (4) That is why military surgeons and emergency room physicians take great time and pains to carefully examine gunshot victims for any additional small holes. Often that is the only indication the person has been shot.
Personal Experience
But let’s be real here. I can cite numerous additional academic and scientific sources that support this article, but I know how cops think. We’re not always the most trustful of academics, especially when it comes to our street survival. So let me add my own personal experience to the data. Please allow me to go beyond the cold facts and share with you why I know what I’m telling you is the truth.
In the mid-1980s I was involved in my first shooting as a police officer. But to give the story context, I must go back to 1982 when I graduated from the Long Beach Police Academy. The first thing I was told by experienced training officers I trusted and looked up to, was to “get rid of that pea-shooter 38 they issued you and buy a real gun with some knockdown power!” Although we were issued .38 caliber revolvers, we were authorized to carry a number of different caliber weapons on duty, the largest of which was the 45 Long Colt.
The .45 Long Colt round next to the diminutive 9 millimeter.
Imagine my surprise when I was confronted by a suspect armed with a shotgun in a dark alley and my Long Colt didn’t live up to its billing. I fired five rounds at the suspect. It wasn’t until I fired my last shot — intentionally aimed at his head — that he went down. I can’t begin to relate to you the surprise and horror I felt when there was absolutely no outward indication I was hitting my target. It was the kind of situation cops have nightmares about.
What actually happened? I fired five rounds at a distance of about twelve feet. The first one missed completely. The second struck his upper leg and broke his femur. The third struck him in the shoulder/chest. The fourth round hit him dead center—in the heart. And of course, the fifth was a headshot. Three of the five rounds created fatal wounds, though only one had immediate results.
Needless to say, I was pretty shaken by the whole thing. Not by the morality of what I’d done; the suspect had already fired at a bystander and taken a hostage earlier. He was also high on PCP. That wasn’t my inner struggle. What shook me was how unprepared I felt; how totally off guard I was taken by what occurred. No one ever told me it would be like that. The reality was contrary to everything I thought I knew about deadly force.
That experience more than any research or study is the reason is why I am writing this article. Police officers risk getting into shootings every day; we need to know the dynamics of how a shooting incident may unfold. It will affect our equipment, tactics, and most important, our mindset. We need to know that rarely will one shot incapacitate an assailant. We further need to be able to explain this when our fellow officers are involved in shootings where multiple shots are fired. The public honestly believes it’s like the movies. Why would we ever need to fire twenty or thirty rounds to subdue an armed suspect? Problem is we can’t teach it or explain it until we understand it ourselves. (5)

Footnotes:
1. Patrick, Urey W., Federal Bureau of Investigation, Firearms Training Unit, “Handgun Wounding Factors and Effectiveness,” p.13. (1989).
2. Ibid., p.9.
3. Ibid., p. 8.
4. Newgard, Ken, MD, “The Physiological Effects of Handgun Bullets: The Mechanisms of Wounding and Incapacitation” (1992).
5. For you visual learners still unconvinced, I highly recommend viewing the Discovery Channel MythBusters segment, “Blown Away,” (Brown Note Episode, Second Season), where the knockdown power myth is visually and scientifically debunked once and for all.
 
Excellent quote. I believe the Long Beach Commander rather clearly implicated Marshall and Sanow along with Hollywood.

Cordially, Jack
 
Thanks for the quote, but I don't think it will do much good. I've said the same for a long time, but no one wants to give up their latest "high performance" ammunition.

Unquestionably a big bullet will do more damage then a smaller one, but neither will do the job if don't hit the right place.
 
Well of course a bullet isn't going to literally push you off balance and onto the ground. The idea that a 1/4 ounce projectile could lift a 200lb man off his feet and push him into the pavement is simply silly.

"Knockdown" power is simply a misnomer referring to the amount of tissue damage a bullet is capable of causing. Much better terms would be Incapacitating Power, or Ballistic Damage Potential. However, Knockdown sounds more "masculine" and sits well in the firearms dictionary next to Takedown (a misnomer for field stripping).

This is just another page in the .45 vs. 9mm debate.

Whatever caliber you shoot best with is the best one to carry. In a time when .45 caliber cartridge revolvers were the newest rage, a man named James Butler Hickok found his favorite gun to be the Colt .36 caliber percussion revolver.

Given that Wild Bill was a legend in his day, with his final day ending before he even reached the age of forty, it can be safely assumed that shot placement IS everything.
 
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I've never viewed "knockdown power" as anything more than a figure of speech. And "one shot stop" is a statistical measure.

On "one shot stop" -- Sanow & Marshall compiled data wherein "one shot stopped the assault."

There's been all sorts of criticisms about Sanow & Marshall's work. One being that many LEO rarely shoot "one shot." Most shoot until the attack stops -- which may entail shooting at a target which is dead and waiting to fall down.

I think Newton et al pretty much provide a useful paradigm: Bigger is better, heavier is better, faster is better. You can crunch numbers and come up with things like "muzzle energy."

Then again, as noted supra -- If you don't hit the target it's all moot.
 
That article perfectly describes why I don't get into "caliber wars".

My feeling has always been that no one wants to be shot, and that's why most gun "incidents" are settled without any shots being fired.

Secondly, if a shot has to be fired in self defense, caliber vs. shot placement is important in a ratio of maybe 10% for caliber and 90% for shot placement (my own arbitrary figures).

Look at it this way; if I'm on the defense, I'd rather shoot the BG in the head with a .22 than in the shoulder with a .45.
Then looking at it in reverse, if I'm on the defense and I get shot, I'd rather I be hit in the shoulder with a .45 than shot in the head with a .22.

So while everyone else argues about all the caliber crap, I happily carry anything from a .380 to a 9mm or a .45, but I feel no less vulnerable with that .380 than I do the .45.
If it's dependable and I can hit where I aim, I'm good to go.
 
Your goal in SD is to get the most lead in the perp's COM/CNS in the shortest amount of time.

This is why the trend toward high power/light weight guns is probably the wrong direction. You can fire more accurate shots in 5 seconds out of a 25 oz .357 than a 13 oz version.
 
It should be noted that the Colt Navy 36's Wild Bill Hickock favored are really a .375"-.380". Firing a soft pure lead 130 grain round ball at about 1000 FPS it was probably a 40 cal when it connected with somebody.
 
Anybody who has done any small game hunting with a variety of handguns(I have) know the folly of handgun stopping power.

True, some calibers(magnums) are better than the rest. Most are about the same level of killers.

I too always thought the BP .36 and .44 better than the ballistics might allow.
 
awe, come on, you mean to literraly knock someone off their feet, i need a REAL cannon?!? how am i going to carry that under my shirt? so much for ccw! LOL! maybe we can all carry time delay c-4 bullets that explode on impact. that aught to do the trick! sorry, i am in a real sarchastic mood this morning!
 
In the early '60s Warran Page published an article calle, "Knock Down Nothing". He was talking about the effect of rifle bullets on deer, but the principle is the same.
A bullet from a 30/06 hits a deer (or a man) and either goes through or stops within the body in 3/10,000th of a second. That's not enough time to push the body anywhere. Page's example was a large safe door, the kind you find in a bank. You can push it closed with one finger, slowly and easily. But if you punch it as hard as you can, you'll break your hand and the door won't move.

That doesn't mean you can't hit the deer (or the man) with a handgun bullet and watch him hit the ground like he'd been electrocuted. It's not the same thing at all.

I'm not suprised that the guy in the article didn't go down. He was on PCP. The lesson is to keep shooting as long as you have a target. You'll know you no longer have a target when you lose sight of the BG and find him on the ground, not moving.

In the entire history of gunfighting, there has never been a case where one of the shooters wished he had a smaller gun that held fewer rounds of less powerful ammo.
 
Damage to the brain or upper spinal cord seem like the only reliable ways to achieve a "one stop shot". It is very ironic that we discuss such matters today since November 22 is the anniversary of President Kennedy's assassination. All who have seen the grizzly film footage of that event know why a CNS shot is so effective.


Timthinker
 
If you were in a gun fight, which would you rather have a Glock 17 9mm with 19 rounds or a S&W .357 mag with 5 rounds?

We know the .357 has a higher knock-down %, but I would rather have the extra rounds of a lesser calibre.
 
I think Newton et al pretty much provide a useful paradigm: Bigger is better, heavier is better, faster is better. You can crunch numbers and come up with things like "muzzle energy."
ARGH!

Who do you think discovered and described (notice I didn't say invented) kinetic energy????

I agree Newton had extremely valuable insights into the concepts of moving objects, but I think you'd be surprised to find what they actually were.
 
Depends on whether you favor "spray and pray", or

"Aim and fire"

Interestingly enough, back when Toyota was breaking into

The American market, one of their strategists

Characterized American business practice as

"Ready, fire, aim",

As opposed to Toyota's business practice of

"Ready, aim, fire."

So there is possibly an ingrained psychological habit

Here, also.

Me, I practice swift aim and fire

With all my firearms,

Whether rifle, shotgun, wheelgun, or semiauto pistol.


isher
 
bigger, faster, deeper! LoL

stopping power: "Where you hit the person and how many times you can hit them."

~ Dr. Vincent DiMaio

To me, that quote is the E=mc² of stopping power and sums it up quite well

good article!
 
And...?

What he says is true as far as it goes. However, a properly placed shot with a large caliber does a better job than a properly placed shot with a small caliber.

His personal account is very revealing, and he doesn’t recognize some of the revelations.

The subject was under the influence of PCP. In real world terms, the subject is not going to be capable of reason or fear. Therefore, no amount of talking or show of force is going to mean squat, to use a technical term.

His first shot missed. There are none of us ‘big caliber’ proponents who recommend missing. None of us claim a miss with a large caliber is effective.

His second shot struck the subject’s upper leg and broke the femur. Do tell. One must ask, how broken was it? The subject on PCP did not feel pain, but if the femur was fully broken, it would not support the subject’s body weight. However, Commander Johnson says the subject was still on his feet. If the round passed through the upper leg and merely cracked the femur, the problem is simply a poorly placed shot. Certainly, a shot on the inside of the thigh may sever the femoral artery and cause a serious loss of blood in a very short time. With that possibility in mind, a larger diameter bullet is more likely to sever a blood vessel than a smaller one.

The third shot struck the subject’s shoulder/chest. Armed with a shotgun, a shoulder joint wound is going to limit the subject’s ability to use the shotgun. Was the subject capable of returning fire? Commander Johnson doesn’t mention a shot on the part of the subject. If the bullet passed through soft tissue only, we have another bad hit. If the bullet hit the shoulder joint, one would expect a severe limitation in ability.

The fourth shot hit the subject’s heart. One wonders at what point the subject was incapable of presenting a further threat. Merely being upright means very little. Falling down means nothing in and of itself; the subject could easily return fire from the ground.

The fifth, carefully aimed shot, struck the subject in the head. The subject then ‘goes down’ and the match is over.

Commander Johnson makes no mention of the time involved. Did he fire five shots over a period of ten minutes, or five shots in four seconds? Since he presents this as a active gun fight, one presumes the exchange took place rather quickly. If the five rounds were fired continuously and immediately, how can the Commander be sure it was his fifth shot only which disabled the subject, and not a combination of shots two, three and four?

In order to evaluate this shooting, we should re-create the event and replace the .45 Colt revolver with something ‘smaller’, say a .38 Special revolver or a 9x19 pistol.

Shot one would still miss. No effective difference.

Shot two in the upper leg. Would the femur be broken? Or would the projectile simply be deflected?

Shot three in the shoulder/chest. A solid shoulder joint hit with either a .38 Special or 9x19 should inflict severe damage on the joint itself, with attendant limitations on joint movement.

Shot four in the heart. This should similarly cause a “bleed out” condition. However, depending on bullet shape, a smaller hole does not bleed as fast.

Shot five in the head. If the round has suitable velocity and power to penetrate the skull, and penetrate into the center areas of the brain, this should result in an immediate incapacitation. However, both .38 Special and 9x19 rounds are noted for deflecting on bone.

What is not answered here speaks to Commander Johnson’s criticism of:
These so called [knockdown power] studies are further promoted as being somehow better and more valid than the work being done by trained researchers, surgeons and forensic labs. They disparage laboratory stuff, claiming that the “street” is the real laboratory and their collection of results from the street is the real measure of caliber effectiveness, as interpreted by them, of course. Yet their data from the street is collected haphazardly, lacking scientific method and controls, with no noticeable attempt to verify the less than reliable accounts of the participants with actual investigative or forensic reports. Cases are subjectively selected (how many are not included because they do not fit the assumptions made?). The numbers of cases cited are statistically meaningless, and the underlying assumptions upon which the collection of information and its interpretation are based are themselves based on myths such as knockdown power, energy transfer, hydrostatic shock, or the temporary cavity methodology of flawed work such as RII. (1)

Commander Johnson carefully selects ONE episode, “…collected haphazardly, lacking scientific method and controls…”. One event is “…statistically meaningless…” and the Commander interprets it based on “… underlying assumptions…” reflecting his own prejudices.

I agree with the proposition “Accuracy and placement cannot be replaced with bullet size.” However, a well placed big bullet will always work better than a well placed little bullet.
 
Harve Curry said:
It should be noted that the Colt Navy 36's Wild Bill Hickock favored are really a .375"-.380". Firing a soft pure lead 130 grain round ball at about 1000 FPS it was probably a 40 cal when it connected with somebody.

I haven't shot a percussion revolver for a few years but IIRC, a .375 lead round ball only weighs about 87 grains.
Even a .44 ball only weighs about 140 grains.

IMO, Wild Bill's lethality with a Navy Colt can mostly be attributed to the fact that Wild Bill was the one using it.
 
Archie,

You make very good points in regards to a single incident setting a precedence mindset. However, my interpretation of the author's use of his own shooting experience was more along the lines of being unprepared for the incident. He mentions how his formal training did not give him a realistic perspective on what would happen when engaged with a determined gunman. He expected to see blood-spurting bullet holes and flinching from hits which did not happen.

You're right though, a single incident is not a determination of caliber effectiveness. Provided that penetration standards are met, increasing caliber size and bullet profile(more semi-wadcutter, wadcutter, and or expansion) are the ONLY proven ways to increase handgun effectiveness. After that, you must work within the limitations of pistol platform, recoil, blast, flash, and other handling characteristics. Compromise those handling characteristics too much, and your combat effectiveness goes way down.
 
I thought accepted doctrine was to keep firing until the threat goes down or the gun is empty? Wouldn't that apply to all calibers?

The OP is set in 1982. The factory ammunition at that time was largely 255 grain lead at about 700 FPS MV. I wonder what the results would have been with Corbon or Buffalo Bore ammo?
 
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