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Myth of knockdown power

zack991

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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.
 

LTTTI

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i just dont believe it. the fact is that being hit by a 45 or 44magnum will have more stopping power than a .22 or 9mm. i just feel more safe using a gun that has sufficient stopping power over something that basically a glorified bb gun :)
 

skidmark

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LTTTI wrote:
i just dont believe it. the fact is that being hit by a 45 or 44magnum will have more stopping power than a .22 or 9mm. i just feel more safe using a gun that has sufficient stopping power over something that basically a glorified bb gun :)

Stopping power has been defined as the percentage of shootings with a particular caliber that resulted in a DRT event. Stopping power does not take into consideration where the bullets struck, just whether the person being shot was DRT or not.

A "big" bullet going "slow" may transmit more power than a "small" bullet going "fast". Then again, a "smaller" bullet going "really fast" may transmit more power than a "big" bullet going "fast". The laws of physics are not going to be repealed by wishful thinking.

If you want to increase the odds of a DRT event, make sure your bullet, no matter what size or how fast, hits a spot where it has the greatest chance of either lowering blood pressure or interrupting the flow of electricity along neural pathways. If one well placed shot has a chance of creating a DRT event, several well plasced bullets only increase the odds of having a DRT event.

That Being Said[suP]TM[/suP], the point of self defense is to stop the threat, not necessarily to cause a DRT event. Sometimes the threat can be stopped without ever having to use the firearm.

stay safe.

skidmark
 

NightOwl

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LTTTI wrote:
i just dont believe it. the fact is that being hit by a 45 or 44magnum will have more stopping power than a .22 or 9mm. i just feel more safe using a gun that has sufficient stopping power over something that basically a glorified bb gun :)

I just feel more safe using a gun with a higher capacity magazine.

It's all about personal preference and knowing that, barring a headshot or a kneecap, you're probably not going to "knock down" someone with a shot or two. Especially larger people.
 

Gordie

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Of course shot placement matters, duh. A .22 in the eye socket is going to have a greater affect than a .44 Mag. in the toe. Still, I don't know anyone who would say that a .22 is a better "man stopper" than the .44.
 

thx997303

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I ascribe to this way of thinking. In a gun fight, expect the worst.

The worst? No caliber hollowpoint will ever expand.

Therefore, I carry a round with proven penetration, a mid weight bullet for caliber, and as much mag capacity as possible.

Following this line of reason, I carry a SA XD in 9mm that carries 16 rounds in the magazine.

Think, if you score a full magazine worth of hits to COM, you have that many chances to hit a vital organ.

Hopefully you would have gone for a head shot by that time, but for the sake of my argument, let's just keep to COM.

Now, an average full size 9mm carries 15 rounds. An average 40 carries 13? And an average 45 will carry around 9.

9mm tends to be .356" dia, 40 around .401", and 45 around .451"

Therefore a full mag of 9mm will leave a hole with a sum total of 5.34" dia, assuming no shots share an entry point, and you have 15 chances at hitting a vital organ.

40 will equal 5.213" dia with 13 chances of hitting a vital organ.

45 will equal 4.059" dia with 9 chances of hitting a vital organ.

That's a difference of 1.281" between the 9mm and the 45. That is the equivalent of the diameter of 3.59 9mm rounds, or 2.84 45s.

Therefore, I believe that the 9mm with similar penetration characteristics to the other 2 rounds, leaves me with the best odds of stopping my threat through sheer volume.

I wont address recoil as that is a personal matter.

I also will not address accuracy as that varies more from pistol to pistol and shooter to shooter than any inherent accuracy in the caliber.

Now, none of the rounds hit a vital organ, so we are out of ammo and relying on blood loss to stop the attacker. Don't let yourself get into this situation, carry spare ammo.

So, we need to look at the surface area of the wound. Since the wounds are a cylinder we will need to find the areas of the top and bottom, or entrance and exit wound, and the area of the sides, or wound channel.

The formula being 2(pi r[suP] 2[/suP]) + (2 pi r)* h where r is the radius of the entrance and exit wound(assuming they are the same size) and h equals the length of the wound channel, or height.

Assuming no expansion, and the FBI minimum penetration of 12"

9mm = 2(pi.178[suP] 2[/suP]) + (2 pi .178)* 12

Which gives you 14.03" of surface area from which blood is being lost from one wound. Giving you about 210" of surface area for the entire magazine.

Assuming my match is correct.

I will finish this later as I don't have the time now.
 

TheMrMitch

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Ah, so. My .45 goes about 500 lbs in foot pound energy.

My .50 BMG ammo exerts about 14,000 lbs in foot pounds.

Would my .50 knock someone down? You betcha!:dude:
 

thx997303

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I would say no, it's only 1/2" in diameter and penetrates.

Does the 50BMG single shot knock you flat when you fire it? Hardly.

Drill Sergeants in basic training said that the .50 would rip your arm off even if it missed.

LOL


Edit: Though it's not fun to shoot from an offhand position.
 

zack991

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The rumors that surround many of these "magical" rounds are very laughable, but the sad part is people take them as fact. They then get into very nasty debates trying to prove something that good old physics proves wrong time and time again. So where does it leave us.....Personal Preference and practice. Simple as that.

1[*]There is no predictable and reliable medical reason for a person to fall and become "instantly incapacitated" from a gun shot with the exception of a wound to the brain stem.
2[*]Sometimes the bullet will produce no visible effect at all. It may take 30-90 seconds or even longer for the person to fall.
3[*]Even if shot placement is good and vital tissue is damaged, it is reasonable to expect the person to remain mobile, active and hostile for 10 to 5 seconds after the shot.
4[*]Pain inflicted on a person, even extreme pain, should never be confused with incapacitation. Neither does the simple act of falling to the ground upon bullet impact constitute incapacitation.
5[*]Bullet effectiveness can be extremely slow even when the bullet perforates the heart, collapses both lungs or cuts open the aorta. Imagine how slow bullet effectiveness can be if vital organs like these escape its damage.
 

riverrat10k

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Anyone who has hunted larger animals, such as deer, knows that shot placement is key, not what you use.

An arrow usually only causes bleed-out; unusual to hit spinal cord. Deer tend to run a long way with a poor shot. Heart-lung area is suggested as this causes asphyxiation also from bleed-out into the lungs.

Rifle shot or shotgun-shot deer can also survive and travel long distances if not well hit. How many hunters have seen or killed previously wounded deer? Many, I expect. And these deer are still wandering around after getting no medical treatment.

For those who don't hunt, watch a hunting show that has film of impacts. Usually the deer jumps in some way, or is knocked off-balance a bit, and then takes off. Very few drop in their tracks.

Good enough proxy for a human as a deer is about the same weight as a man.
 

Tomahawk

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I saw a buck take a mushrooming30-06 through both lungs, jump up and kick like a mule, and then run like hell. We found pieces of lung tissue on the tree leaves behind where he had been hit, and we found him dead in the brush about 75 yards from where my friend had hit him. The exit wound was considerably larger then the entrance. A 30-06 delivers an assload of energy, but the buck did not get "knocked down", despite the lethal wound.

Another time I saw one get hit and go right down, but that was because the .308 bullet shattered the bone in the buck's front leg before entering the rib cage area.
 

Interceptor_Knight

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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 be of sufficient diameter to promote rapid bleeding.





http://www.thegunzone.com/quantico-wounding.html
 

Ohio Patriot

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thx997303 wrote:
I would say no, it's only 1/2" in diameter and penetrates.

Does the 50BMG single shot knock you flat when you fire it? Hardly.

Drill Sergeants in basic training said that the .50 would rip your arm off even if it missed.

LOL

Completely agree.

I also have a .50 BMG, and have shot it offhand on numerous occasions. It didn't knock me over, hence it won't knock down a person you've shot via momentum alone.
 

TheMrMitch

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Your won'tlose your armfrom a near miss....HehHeh....we all know that.

The shooter will not get knocked down because the weight of the rifle (my AR50 = 38 pounds) plus the muzzle brake effectively dampens recoil.:dude:

Shoot it WItHOUT the brake.:shock:
 

thx997303

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Given it would definitely be very very uncomfortable.

But I don't believe it would knock you over.

Anyone remember the video of people shooting the .577 tyrannosaur? That had no muzzle break and produces 10,180 ft pounds.

Hmm, maybe not a perfect example.

Better one, the 2 bore. Massively powerful, would knock down a man who did not stand correctly. But this weapon fired a 3500 grain projectile measuring 34mm. This weapon weighed a mere 20 pounds with no muzzle brake and produced over 17000ft lbs of force.

Yet, it could be fired from an offhand position by a man who knew how to properly fire it.
 

TheMrMitch

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These things are merely things of which we macho men toss aroung whilst flexing our abs and roaring about what we think actions will occur.

No matter how much foot pounds, or in some cases fruit pounds, are expended, there will be variables off each end of the spectrum and I enjoy the comraderie exhibited whilst partaking of the discussion.:celebrate
 

thx997303

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But of course. I would love to have a chance at firing a 2 bore, unfortunately, in order to do so, I would need to build one.

I would probably shoot it once and hang it on the wall! Lol, beast of a thing.

Imagine shooting a deer with it!
 

WheelGun

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Just read the news. So many bad guys shot by cops or armed civilians are walking around with little round scars where the bullet hit.

Think about Bernie Goetz's subway assailants. The only round that really did anything permanent was a second round fired point blank after the fight was over.

The only positive outcome of that scenario was that the BGs lost interest in victimizing Goetz.
 

fully_armed_biker

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The reason the 1911 came to fruition was because the Moros in the Philippines used a combination of drugs, leather body bindings, and religious rituals to enter an altered state of consciousness that left them impervious to pain...and the .38 Long Colt round that the standard issue sidearm of the day was chambered in. It was determined that a .45 caliber round would havesufficient stopping power to overcome the Moros. John Moses Browning (one of my personal heroes) developed what we know as the .45 ACP round and designed the 1911 around the round.

I've worked for the Army of 12 years and have heard stories directly from soldiers that have been in Iraq and Afghanistan about the deficiencies of the 9MM Berettas they currently carry..and the lack of stopping power despite their "bottomless mags."So much so that I know of several officers that have brought their own personal 1911s and ammo with them. Several elite military units have abandoned their 9MMs altogether because of their lack of stopping power.
 
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