Posted on 10/02/2007 9:15:49 AM PDT by 7thson
Hey, I got a question for all the firearm experts/enthusiasts on Free Republic.
Speaking to my grandson recently - he is 16 - he told me a episode of Mythbusters where the look at the 'myth' shown in movies when a person gets shot they get blown back. The Mythbuster people concluded it was false by shooting a dead pig and a dummy. Also - and this stood out to me right away - they said that according to Newtons law - every action has an opposite reaction - that when the person gets blown back it would mean the shootist would get blown back the opposite direction.
Now please correct me if I am wrong because I do not know much about firearms. But I told my grandson that mythbusters got it wrong. First, I said that certain firearms were developed for the sole purpose of putting people on their arse. And two - they got the law wrong. I said that when you fire a gun the reaction is the recoil. And that when the bullet hits the person, the opposite reaction is getting pushed back.
Can someone tell me if I am wrong or right. Also, does anyone know where I can link to the political belief test that indicates whether someone is a conservative, liberal, Stalinist, etc?
Now, I was under the impression that a firearm was built for the US Army during the Philippine Insurection back in the 1900's that would knock down on their arse who they were fighting because the natives were so popped up on native drugs that ordinary pistols did not stop them. Is this true?
I guess the myth - remember I did not watch the episode - is being knocked down and back several feet. Now, maybe a gun will not knock you back 10-20 feet but are there not firearm caliber that once you are hit, will put you down?
Also, anyone know of a link for that political belief test?
I’ve never been shot and I’ve never been hit by a baseball bat. Lucky, I guess. 8-)
Agreed, but we are talking about a .22 or a .44 like in the old western movies.
The myth was the body flying backwards not falling down.
Umm... K? Am I refuting that somehow?
depends on the caliber of the round and the type of round.
You get hit with a .22 you’re body is not going to go backwards
You get hit with a .45 you’re going to go back and down.
I reckon it would depent in no small amount upon whether the bullet exits the body or not. if it does not exit the body, then it’s entire energy is transferred to the body and the mass/acceleeration thingie kicks in.
if the bullet goes through the body, then some of the energy is absorbed by the body, and the remainder remains with the bullet.
there’s a classic picture of a bullet passing through an apple. the debris etc., is such that if you didn’t see the projectile in the pic, you couldn’t tell from which direction it came.
Actually, you would probably be moved a greater distance with a baseball bat. The surface area impacted would be considerably greater than a conventional rifle shot. Because there would be no penetration of being hit with a baseball bat the body effectively absorbs the impact causing motion in the same direction as the hit. Had "MythBusters" done this amatuer experiment with a bullet proof material covering the hog their results would have probably been different.
To oversimplify slightly: if it knocked down the victim, the recoil would knock down the shooter as well.
(”Knocked down” as in “blew him off his feet”, not “caused enough damage he couldn’t stand up”.)
Some observations:
There is a real effect that people think they are supposed to fall back or fall down when they get shot. People do this not because of the physics of the impact, but because of their muscle reaction, conscious or subconscious. The movies have had a big effect on this.
Recoil is comparable to “knockdown” power (assuming the bullet delivers all its energy to the target, and does not carry thorough with much energy remaining.) However, keep in mind that recoil is usually anticipated and braced against, while a bullet impact is not.
Imagine a “bullet catcher” weighing 200 pounds (Say, a steel plate on little car on rails). It is hit by a bullet weighing 1/10th pound (a 700 gr. 50BMG - conversion is 7000 gr./lb.) at 2600 feet per second, and all the energy is transferred to the target. The momentum of the bullet is transferred to the target, which weights 2000 times as much. Thus, the target will end up moving backwards at 1/2000th the velocity of the bullet, or 1.3 feet per second, or about 1 mph, which is a very SLOOOW strolling speed. But enough to make a guy fall backward, when he has just been traumatized.
Didn’t JFK get pushed forward when he was shot?
Under that condition (perfect sternum hit, well-supported by skeletal structure), the impact energy is optimally (but still imperfectly) converted into a push backwards. This push will indeed be a push back, but far from a “thrown back off his feet” kind of push.
We’re so used to being stable on our feet that we hardly consider what happens when we’re not. Think about the body mechanics: a slight reward push will throw center of gravity far enough off-center that you’ll fall ... and your legs being essentially long hard levers with a single stiff joint in the middle, the fall will push the torso & head WAY off center - resembling “thrown back”. Go ahead, try it now: stand up, lean back slightly, and see how you fall - your head (when you wake up) will be around 6’ from where it started, even though you only initially moved a couple inches.
Upshot: any “thrown back” imagery anywhere close to real will have far more to do with gravity & body mechanics than ballistic impact.
Penn & Teller covered that in their book “How To Play With Your Food”. The terminal ballistic behavior is counter-intuitive, and they demonstrate it.
You get hit with a .45 you’re going to go back and down.
And down not because of the impact, but because of the fact that you are wounded seriously, and probably want to take cover. A 45 ACP has 1/3 the mass, and less than half the velocity of a 50 BMG, so it has the same effect as being hit by a bus that is going about 2 inches per second (and stops after it hits you.)
I am saying that the myth they were testing was the body flying backwards as it gets filled with lead, not just falling down. I was not refuting what you were saying because what you said is what they proved. The mass of the bullet is not sufficient to make a body fly backwards unless the guy shooting was also flying in the other direction.
Sorry for the confusion.
That was the one problem with the Mythbusters setup. They didn’t test to see if the bullet could destabilize a 6-ft structure so it would topple over, they hung the pig from a hook and checked if it would be pushed off the hook. There was friction to overcome, and the bullet didn’t have the force to overcome that friction.
Still, they were correct that the same force tries to knock down the guy shooting. And in fact, if you stand with your feet together straight up with your heels touching a small board so you can’t step back, and you shoot a good-sized rifle, you will end up falling backwards.
A person who is shot and isn’t expecting it might therefore fall backwards because they wouldn’t step backwards to balance themselves.
But the force of a bullet, even stopped by kevlar, is less than the force of a fastball. It could knock the catcher over if the catcher didn’t adjust to receive the pitch.
Having been shot once (7.62x39 through the right shoulder), it hurt like hell, but didn’t knock me down or even spin me around. However, the first time I ever fired a .50BMG Barrett, I did it standing (on a dare),it knocked me flat on my ass.
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