I want to start off saying something that might surprise you.
"I hate Mythbusters."
You'd think, considering I am a huge nerd, that I'd love that show, right?
My problem here is that they all too often DON'T do experiments in a way that scientifically proves OR disproves their hypothesis, and then they present their actions as "proof" that something is true or false.
Considering, you know, they're Mythbusters, people who are unable to think through things themselves often then consider them an authority on things.
Now, this came up as part of an article on a completely unrelated site, and my nerd fury was aroused beyond my powers of self-control by seeing one really, really stupid thing that I see - often - when people talk about firearms on the internet.
That being, "proof" that a bullet cannot cause a body to go flying, as they so often do in Hollywood.
Almost inevitably, someone discussing this will cite Newton's Third Law - for every action, there is a reaction - as proof that a bullet can't do that without also sending the shooter flying.
Those people failed physics in high school.
They also frequently cite Mythbusters episodes 25 and 38, in which the Mythbusters "proved" that a bullet wouldn't make a body go flying on impact.
Now, I grant that Hollywood exaggerates this; but the problem with both the failed physics students and the Mythbusters, here, is that any hunter can tell you that this is bullshit and a round from a hunting rifle will knock a full-grown deer ass over teakettle if you hit it in the shoulder.
Errr, sorta like what happens if you shoot a human.
So, how did the Mythbusters "prove" this wrong, if it isn't, and how did the failed physics students manage their dismal grades?
Let me break the several factors down one at a time.
First, let's dispel the myth about Newton's Third Law.
When you fire a weapon, the energy the bullet has at impact isn't imparted to it instantaneously; the gun doesn't shoot bullets by magic, and it doesn't use teleportation. When a round is fired, the gunpowder in the cartridge is ignited; it burns very quickly, creating a moving wavefront of expanding hot gas. This wavefront pushes the bullet, accelerating it down the barrel at ever-increasing speed; the acceleration ends when the bullet exits the barrel and the gas disperses (that's the "muzzle flash") and the bullet then travels to its target at the speed (this is the "muzzle velocity") imparted to it by its time in the barrel.
What this means is that the shooter in fact DOES absorb most of the energy the bullet takes with it; but the shooter absorbs it as a steady (if brief) push, rather than an impact. (Although, if the firearm is big enough and there's enough recoil to be had, this doesn't matter, as witness this video of an inexperienced shooter getting knocked in the forehead by his scope while firing a .50 caliber rifle.)
I say most, because most firearms have both recoil-dampening springs and other such devices, they also typically vent some amount of the gas in a direction that is safe for the shooter but opposing the direction of bullet travel; say, down, or to the sides. This cushions the recoil for the shooter even more, without removing the force from the bullet.
Now, that said, what happens when the bullet hits the target?
Instantaneous impact. All the kinetic energy carried by the bullet is imparted to the target instantly. Now, this can take two forms: either the bullet remains within the target - as in a bone hit on a deer - in which case the target goes flying, or the bullet blows clean through the target, in which case it carries most of its kinetic energy away with it, causing damage through hydrostatic shock.
Right. So what makes that crucial difference? Two factors: first, the sheer quantity of kinetic force imparted to the bullet by the firearm - primarily a function of barrel length thanks to the longer acceleration time - and second, the type of bullet itself.
A rifle imparts far more kinetic force to a bullet than does a pistol of any variety; you can test this at home, if you're so determined, by using both a rifle and pistol chambered for .22 long rifle ammunition, and firing both at a target. the pistol will impart much more force to the target as target motion, and the rifle will blow nice, deadly (though little) holes right on through it - thanks to the barrel length.
The bullet matters as well; a "jacketed" round, for those of you who care but don't know, is a lead slug physically wrapped in a harder metal, like steel or copper, so that the bullet doesn't expand when it hits the target; the specific purpose of a jacketed slug is to increase target pass-through. In other words, the ammunition is specifically designed to KILL the target, by plowing great honking holes through it, as opposed to knocking it down (what's called "stopping power.")
For "stopping power," - in other words, the power to make your target do cool backflips - you use hollowpoint or frangible bullets, which are designed to expand when they hit a target, thus imparting all their energy to the target and NOT flying on through to hit innocent bystanders.
Now, you may be wondering, where does Mythbusters come into all this?
In both episodes, they used rifles to fire jacketed rounds at targets, then claimed that this proved that the bullets had insufficient(?!) force to knock the targets down.
Howinthehell did the bullets blow all the way through the targets, then?
In order for their experiments to have been accurate, they should have tried both rifles and pistols, in several different calibers, with both hollowpoint and jacketed ammunition.
What they would have discovered is that the slower, lower-powered rounds were far more likely to actually send a target flying, while the faster, high-powered rounds would blow right through the targets with ease.
I am totally unable to comprehend how someone can seriously misunderstand physics to an extent that allows them to proudly display a fucking car door with bullet holes that go all the way through it and still claim that a bullet doesn't carry enough energy to knock down a human.
Here, I'll show you an easy way to prove those people to be idiots: hit them with the car door. I guarantee they fall down, and are far more damaged than the door.
If something can blow holes through steel, guys, it can blow holes through you. Using armor-piercing ammunition specifically designed to GO THROUGH FUCKING ARMOR - not to knock you down, but to pierce the target - to attempt to prove that bullets can't knock you down is goddamned retarded.
Also, Mythbusters fails 10th grade physics.
