Page 1 of 3 123 LastLast
Results 1 to 10 of 30
  1. #1
    Instructor JimConway's Avatar
    Join Date
    Mar 2005
    Brookline, NH and Pepperell, MA

    Default The truth about handgun knockdown power


    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)

    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.

  2. #2


    Interesting article.
    I have always been of the school that it is about placement and penetration. Center Mass hoping to get a vital organ or nervous system, and use a round that will penetrate the clothing and skin to get to the vital organs with enough force that they will be damaged to the point the threat will be immobilized.

    The author may indeed be correct about the reality vs myth of people getting knocked on their ass by a single gunshot, but choice of caliber, gun, and bullet characteristics to indeed play a huge role in stopping someone.

    If you had a choice of a .25 or a .40 what would you choose?
    even a .380 as compared to a 9mm. In my reading I have seen many people suggest that the 380 is a marginally effective round and doesn't penetrate enough to stop any attacker with enough certainty that it is an effective all around CCW round. That being said a well placed shot from a 380 is better than a flesh wound from a 9mm shot by someone not proficient with their weapon.

    Besides I don't want the bad guy blown across the room by my first shot. I want to be able to get that second shot on the money and I can't do that if he or she is in flight.

  3. #3
    Registered User
    Join Date
    Aug 2007
    Sandown, NH


    Great info, thanks for the post.

  4. #4


    Dude, you just harshed my buzz... You mean bad guys don't scream and fly through the air when Arnold shots them? Next you are going to tell me there is no such thing as the never-ending ammo supply. These liberals in Hollywood just can't be trusted.
    In life, if you don't risk something, you risk everything.
    *Support Comm2A in the fight to protect MA gun rights in the courts.*
    Follow Comm2A on Twitter and Facebook
    The above post does not reflect the opinions of any organization I may be associated with. I Am Not A Lawyer

  5. #5


    I know of only 3 ways to stop a threat...

    1. Through a skeletal breakdown (the attacker is rendered incapable of holding a weapon due to projectiles breaking his skeletal system) ***very unlikely.

    2. Through shutting down the attacker's central nervous system (shot through the brain) ***handguns have a very difficulty time penetrating the skull...head is small...very difficult to do.

    3. Through blood loss (an adult needs to loose approximately 1/2 gallon of blood before he looses conciseness...this takes as long as 30 seconds). ***this is what we train to do...shoot as many times as needed to stop the attacker. I just finished reading an autopsy report were the bad guy was shot 16 times (.223 hornady tap) and 9 times (.40s/w)...he expired on scene, however, he was still fighting with officers while being cuffed...slight traces of marijuana in system.


    While shot placement is important it must also be noted that the volume of shots placed is absolutely critical.

  6. #6
    Instructor JimConway's Avatar
    Join Date
    Mar 2005
    Brookline, NH and Pepperell, MA


    Think about the reports in terms of advice normally given about selecting a handgun for defense. "Carry the largest caliber in a gun that you can shoot accurately" Bigger calibers make bigger holes that bleed more. Simply put, this is all about shot placememt under extreme stress.

    Glockaholic - if your first shot blows the BG across the room, it is Very unlikely that he is still a theat. Now get up off the floor, dust yourself off, and call 911.

    i have spoken with a number of officers that have had to shoot and they all commented that they did not see their bullets hit the BG. I recently saw a film of a man that shot himself in the temple with a .357 magnum. After the shot all that he did was to slump down (dead) in the chair. There was no entry or exit wound visible

  7. #7
    Instructor JimConway's Avatar
    Join Date
    Mar 2005
    Brookline, NH and Pepperell, MA


    "While shot placement is important it must also be noted that the volume of shots placed is absolutely critical"

    I think that you have your statement completely backwards. A whole bunch of marginal hits is going to have little effect as opposed to some well placed hits. To get the required blood loss to have the BG lose consciousness in 30 seconds, you have to hit something major like the heart, lungs or the aorta.

    In addition your three ways to stop a threat, there is a fourth way - a psychological stop. This is a minor hit or a complete miss that causes the BG to just quit just like in the movies. Remember that in the movies "one shot stops" are the norm. This does happen more often than one would thing, just do not depend it

  8. #8
    NES Member Nickle's Avatar
    Join Date
    May 2005
    Vermont, a Free State


    The study of Wound Ballistics teaches you some amazing things.

    Even RIFLE bullets don't "knock them totally down".

    I always stump people with a good one.

    Which has more power, .40 S&W or .45 ACP, assuming both are using Hollow Points, and the .45 using 185 gr bullets (which actually are said to have higher energy than the 230 gr loads)?


    Neither, for all practical purposes.


    Because energy (power) is measured as a function of wieght and velocity, and the 5 grains and maybe 50 fps velocity difference between these 2 isn't enough to amount to spit. Yet, some folks argue it ALL the time. Truth be known, there's more than enough velocity variation from gun to gun to make the comparison irrelevant.
    Terrorism only works on those that allow themselves to be terrorized. The rest of us get even.

    "people sleep peacefully in their beds at night only because rough men stand ready to do violence on their behalf" George Orwell

  9. #9



    I agree with what you have said. My point was that there is a requirement of multiple properly placed shots in order to get to the 1/2 gallon figure in as short of a time period as possible.

    I omitted the psychological phenomena of the fighters giving up. This appears to happen rather frequently. Years ago the FBI did a study on this phenomena and found that many of their agents were giving up during fights because they "thought" they were incapacitated. The same study found that many of the bad guys did not know they were "supposed" to give up.

    Hence, the idea of a "one shot stop" can lead a fighter to prematurely disengage during a fight.

  10. #10
    Registered User jar's Avatar
    Join Date
    Apr 2007
    Needham, MA


    The whole ballistics argument reminds me of a catchphrase from another forum. AHS, ASS, HTH, HAND. All hardware sucks, all software sucks, hope that helps, have a nice day.

    My opinion is use whatever you'll ACTUALLY CARRY, and can make GOOD HITS with QUICKLY.

Page 1 of 3 123 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts