Quantcast
  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

The myth of knockdown power continues...

Discussion in 'General Gun Discussions' started by backbencher, Feb 5, 2013.

Thread Status:
Not open for further replies.
  1. backbencher

    backbencher Member

    Joined:
    Dec 13, 2005
    Messages:
    397
    Location:
    Texas
    So - 1 cocky soldier posits the following:

    Given a M9 pistol, a 9x19mm NATO ball round, & a SAPI armor plate in a vest, said round discharged into the vest will knock the wearer down.

    We want it to be so, therefore it must be so, hang the physics!
     
  2. Dr.Rob

    Dr.Rob Moderator Staff Member

    Joined:
    Dec 23, 2002
    Messages:
    14,744
    Location:
    Centennial, CO
    There's plenty of video out there to debunk this.
     
  3. mrvco

    mrvco Member

    Joined:
    Jun 1, 2011
    Messages:
    697
    Location:
    Colorado
    ~ 13 Newton Seconds
     
  4. JohnKSa

    JohnKSa Member

    Joined:
    Jan 1, 2003
    Messages:
    12,533
    Location:
    DFW Area
  5. Jorg Nysgerrig

    Jorg Nysgerrig Member

    Joined:
    Apr 13, 2006
    Messages:
    7,823
    Depends if is +P+ or not.
     
  6. backbencher

    backbencher Member

    Joined:
    Dec 13, 2005
    Messages:
    397
    Location:
    Texas
    Given a 160 lb human being is more than 1,000,000 grains, our good soldier obviously can't be bothered w/ math. Unfortunately, he's an artilleryman...
     
  7. Fast Frank

    Fast Frank Member

    Joined:
    Feb 17, 2007
    Messages:
    1,087
    Location:
    Houston, Texas (Woodlands)
    I think it's more about semantics than anything else.

    Yeah, we have all seen a pistol round knock down a bowling pin. It's just about all a pistol round can do- anything much bigger than a bowling pin stands a good chance of absorbing the hit and staying upright.

    But going back to the vest wearing man and the nine millimeter...

    I have experimented with a "Timed Out" vest before. (They have an expiration date)

    After shooting it with everything from a .22lr up to .44mag, I can tell you that it does in fact stop the bullets from penetrating.

    I can also tell you that it knocks the crap out of whatever is behind the vest.

    I know that it's not scientific, but I tried to duplicate the dent left in a pine board that was behind the vest when it got shot with .45acp.

    It turns out that smacking the board with the ball end of a 16 ounce ball peen hammer with everything I can put behind it pretty much makes the same kind of dent in the wood that the .45 leaves behind the vest. Now, I'm not Thor or anything like that, but I don't know anybody that would let me hit them for all I'm worth in the chest with a 16 ounce ball peen hammer.

    And that brings me back to knockdown power.

    I'm pretty sure that a grown man will in fact end up on the ground right after catching a pistol round in the chest while wearing a vest. The energy transfer is still going to be massive and painful, and it just might turn a man's lights off for a little while. It's absolutely going to knock the wind out of him. Probably break some ribs too.

    Now, I realize that the pistol round doesn't have enough power to literally take a man off his feet and throw him down...

    But if he hits the ground right after taking the bullet, can't we call that a knock down?

    I'm pretty sure that nine out of ten people watching a man "BangFlop" from a pistol round would say he was knocked down.

    It's semantics. http://en.wikipedia.org/wiki/Semantics

    If we can't call a man that hits the ground in the same second that a bullet impacts his vest "Knocked Down", then what DO we call that?

    Here's a definition from the online dictionary:

    knock down
    1. To bring to the ground with a blow; topple.
     
    Last edited: Feb 5, 2013
  8. JohnKSa

    JohnKSa Member

    Joined:
    Jan 1, 2003
    Messages:
    12,533
    Location:
    DFW Area
    If you stick an icepick between someone's top cervical vertebra and into the skull foramen the person will instantly drop like a stone. But he will fall because his central nervous system was damaged, not because he was knocked down.

    If you shoot someone with a taser, there is virtually no force imparted to the person via the impact of the darts, but the person will instantly fall to the round because the electric impulse will impair his ability to control his muscles.

    If a person is dropped from an airplane, he will end up on the ground, but not because he was knocked down.

    If a person loses his balance and trips, he will end up on the ground even though nothing knocked him down.

    There are many different ways a person can end up on the ground without being knocked down and therefore it's inaccurate to say that merely because a person ends up on the ground he must have been knocked down.
    We can say he fell down from surprise, from the pain of the bullet strike, or any thing else that accurately describes what actually happened.

    By the way, the OP was responding to the following claim: "Given a M9 pistol, a 9x19mm NATO ball round, & a SAPI armor plate in a vest..."

    Soft body armor employed with an armor plate backing will allow a person to soak up pistol bullets so effectively that they may not even realize they have been shot. They certainly won't be knocked down.
     
  9. Sam Cade

    Sam Cade Member

    Joined:
    Sep 9, 2005
    Messages:
    5,228
    Location:
    Rural Kentucky, surrounded by Amish
    Now go smack a 200lb log with equal force and see how much it moves.
     
  10. jwh336

    jwh336 Member

    Joined:
    Jan 29, 2013
    Messages:
    25
    I can't help but think of those two bank robbers in California back in the '90's...
     
  11. ofitg

    ofitg Member

    Joined:
    May 17, 2010
    Messages:
    405
    During my crazy, misspent youth, I witnessed one guy absorb a torso hit from a blackpowder .44 pistol with a Second Chance vest - it smarted like the dickens and left a bruise, but he didn't go down.

    I saw another guy take a torso hit from a .38 Spl while wearing a Second Chance vest - again, he did not enjoy it at all, but he stayed on his feet.
     
  12. Fast Frank

    Fast Frank Member

    Joined:
    Feb 17, 2007
    Messages:
    1,087
    Location:
    Houston, Texas (Woodlands)
    See? That's semantics at it's best.

    You have an idea in your mind what the word means in regard to this situation.

    But in another situation, the meaning might be different.

    Say I accidentally bumped your flat screen TV with my elbow, and it wobbled for a second and then fell on the floor.

    I'm pretty sure you would jump up and demand payment because I Just knocked down your TV and broke it. By the given description, that's exactly what happened.

    Would you accept my argument that the amount of pressure applied by my elbow was not enough to take your TV off it's feet and throw it violently to the floor, therefore I could not have knocked down your TV?
     
  13. wooly bugger

    wooly bugger Member

    Joined:
    Dec 8, 2009
    Messages:
    98
    This is important, because the antis use the fact that what's his name was wearing body armor in the Colorado movie theater shooting as a complete refutation of CCW's effectiveness.

    If a 9mm is something like a bruising punch, I'm guessing 4 or 5 hits would at least give him pause and maybe set him up for a head shot.
     
  14. Airbrush Artist

    Airbrush Artist member

    Joined:
    Jan 10, 2013
    Messages:
    333
    Location:
    Kettering,Ohio
    Sometimes Beer Knocks Me down...
     
  15. Bartholomew Roberts

    Bartholomew Roberts Moderator Emeritus

    Joined:
    Dec 26, 2002
    Messages:
    14,613
    Location:
    Texas
    I think people, particularly hunters and soldiers who see living things shot, confuse "knockdown power" with neural response. I once popped a rabbit in the head with a .22LR and it flung him backwards 6-7' in the air... See how powerful .22LR is? Except that wasn't what happened... His scrambled brain signaled his leg muscles to contract and he jumped even as he died... The visual effect makes it look like the bullet blew him straight up into the air; but it is just the last message of a shattered nervous system.
     
  16. mbt2001

    mbt2001 Member

    Joined:
    Dec 5, 2005
    Messages:
    2,902
    Location:
    Texas
    +1

    I have had similar experiences. Bullets and guns are not magic charms that end fights.

    In fact, one of the best "hollywood" gunfight scenes I have ever seen was at the end of Brooklyn's Finest. Richard Gere shoots a perp in the pump with a .38 and it is a failure to stop scenario. Very intense.
     
  17. Backpacker33

    Backpacker33 Member

    Joined:
    Oct 4, 2009
    Messages:
    221
    Location:
    Wisconsin. Say not "I know," so much as "I wonde
    I was hit in the chest, about 2.5 inches below my right nipple with a 9mm Hydrashok from three feet. The shooter used a Glock 19. I was wearing armor. I remember the flash but do not remember hearing the "bang." Next thing I have any recollection of was my team mates ripping off my clothes and armor. I felt as though a hot poker had been punched into me. The bullet penetrated the armor (we're talking almost 20 years ago) and penetrated my ribs. It stopped in my liver. According to the others, I fell the moment I was hit. Consensus is that this was mostly a reflex action on my part, attempting to jump back from the threat and reacting in shock. Though I don't remember the few seconds in between the flash and people helping me, this is probably the well-known effect of the mind not being able to keep up with the enormous amount of info that comes in so short a time. In my case, it went into "pause." I don't remember being afraid, just knowing I was totally dependent upon others for my well being. The paramedics said I did go into shock, but I feel as though I remember the entire painful ride to the hospital, with them fussing a lot and constantly talking to me. Last thing I remember as an IV-drip was put into my arm to deliver anesthetic, was asking if I could stay awake for the operation. HAH!

    That was actually the second time I was shot. First time was in the head. I remained fully conscious and physically able and took care of my own flight from the threat. Ooooo did that hurt! And bleed.
     
  18. taliv

    taliv Moderator

    Joined:
    Oct 23, 2004
    Messages:
    22,146
    you guys aren't fooling me. i've seen how they fly in the movies.

    funny how it's always the bad guys that fly 10' when hit, and the good guys just sort of get a constipated facial expression
     
  19. Outlaw Man

    Outlaw Man Member

    Joined:
    Jan 18, 2007
    Messages:
    1,870
    Location:
    Cleaning my guns.
    I nicknamed my truck "9mm," just so I can say things like that. :D
     
  20. meanmrmustard

    meanmrmustard Member

    Joined:
    Jun 14, 2011
    Messages:
    4,225
    Location:
    Missouri
    I'm on here with educated folk, but I'm going to say it anyway:

    The force required to knock the average human down would implicate the same amount of force in recoil on the shooter.

    While a bullet might exhibit traits that make a perp fall faster, you're not knocking anyone down.
     
  21. gspn

    gspn Member

    Joined:
    Jun 10, 2006
    Messages:
    2,184
    No way a 9mm could do that. now...if it were a 10mm...
     
  22. 481

    481 Member

    Joined:
    Feb 22, 2009
    Messages:
    1,950
    Knock-down power? A 9mm 124 gr. @ 1250fps has only 3.061 N•s of momentum. Not very much.

    A 155mm round will do it, but then there ain't much left anyway so it's kinda academic, ain't it? :D
     
    Last edited: Feb 5, 2013
  23. Onmilo

    Onmilo Member

    Joined:
    Jul 26, 2004
    Messages:
    9,773
    Location:
    Illinois`
    Let someone shoot you in the kneecap with a .22 solid and if you stay on your feet you can debate the "knockdown myth" all you want...
     
  24. meanmrmustard

    meanmrmustard Member

    Joined:
    Jun 14, 2011
    Messages:
    4,225
    Location:
    Missouri
    That's not knockdown, that's falling.

    ...and it's still a myth, a fictional happenstance in cheesy movies, and just as damaging to shooter as it is to whom is shot.
     
  25. Sam Cade

    Sam Cade Member

    Joined:
    Sep 9, 2005
    Messages:
    5,228
    Location:
    Rural Kentucky, surrounded by Amish
    If we want knockdown power from a pistol we are going to need one that fires Powder Blue 1976 Ford LTDs.
     
Thread Status:
Not open for further replies.

Share This Page