There are a lot of misconceptions about bullets and how they work. There is no voodoo to what a projectile does. There is no mystery. There is only ignorance and misunderstanding. So, the next time you see a full color 2 page advertisement for some wonderfully tactical ammunition that is obviously used by every Special Forces Ninja out there… take it with a grain of salt.

Let’s take a look at how a bullet stops a bad guy. Lots of people who read gun magazines and little else use a certain phrase way too much. “One Shot Stop”. These are the same guys that go on and on about bullets and loads and are always searching for that Magic Bullet. The “Black Arrow” that will slay evil even if it misses. There is no such thing. Some hollow points are better at certain aspects of bullet performance than others… but in effect, they all do the same thing. Make holes. The trick is to make the holes where they do the most damage. This is called “Shot Placement” and is the most critically important aspect of a bullet wound.

There is more than one way to skin a cat. There is also more than one way for the bullet to stop a threat.

1. Hydraulically. Making the target bleed out. Once a human looses enough blood, he goes into Hypovolemic shock. Hypovolemic shock refers to a medical or surgical condition in which rapid fluid loss results in multiple organ failure due to inadequate tissue perfusion. Most often, Hypovolemic shock is secondary to rapid blood loss (hemorrhagic shock). The cardiovascular system initially responds to Hypovolemic shock by increasing the heart rate, increasing myocardial contractility, and constricting peripheral blood vessels. This means to you and I that shots to extremities get a biological response that naturally reduces the loss of blood. A center mass hit is required to insure this rapid loss of blood. If you aim Center Of Mass (COM from now on) the bullet has the best chances of penetrating deeply into vital internal organs.

2. Structurally. The human body is built on a solid framework we call the skeleton. Certain bones in the skeleton support the whole weight of body. I’m talking about the legs and the pelvis. A shot that hits and shatters one of these bones disrupts the structure and causes a collapse. Actually making this shot is difficult as the legs are much thicker than the actual bone. There is another downside to that kinda of a shot, and that is the subject may still have some fight left in him. He may not be able to stand, and probably wont be doing any tap dancing for some time, but if he is armed, he is still a threat. He just might still be able to take a shot back at you.

3. Electrically. CNS. Central Nervous System. The nervous system in the human body is basically like electric wiring and all the wires run to the brain via the conduit called the central nervous system. It’s located in the spine. Sounds easy enough, but really this is where it gets complicated. If you fire a shot that hits the spine and severs the CNS, you’ve disrupted the electrical system. But only everything “Down Stream” from that wound. That could be a problem. If it was a COM shot and you hit the subject in the spin in the middle of the back, he will not be able to use his legs, but the upper body is still connected and functional. The subject could still return fire. The place that you want to hit to turn the subject off like a light switch is a very small target. You want to hit the Medulla Oblongata. It is the size of a Grade A Medium egg, it is nested in a protective covering of very solid bone. Making that shot with a handgun is unlikely. Unless your subject is bound and kneeling in front of you and your about to give him the Mafia Classic “Two shots to the back of the head”… don’t even think about taking that shot. In such a dynamic event as a gunfight, you’re a fool if you think your going to be making that kinda of a shot. Even bench rested. Your target is small and the subject is moving… Take the shot you can get and aim COM. Now, if your in the urban police sniper role and you have a nice .308 rifle with a high power scope, then MAYBE this shot is an option. Especially if you only have one shot it has got to stop the subject instantly… that is what you want to hit. Like a light switch. Effective – but hard to get.

4. Psychologically. Getting a bullet wound, even a minor can have a drastic effect on someone’s moral motivation. Some people, they see a little blood, and they just lose the will to fight. They give up right then and there. They may even go into shock. Some people have even died from this, when the wound its self was not even life threatening. Although this does and can happen, don’t bank on it. You might think that the bad guy might stop having been hurt. There is a pretty good chance if they were not bright enough to stop at the sight of an aimed gun, they are not going to stop with a mere wounding. Sometimes getting hurt just makes the subject all the more dangerous. Your shot may have been a lethal one and that guy will die… but in the mean time, he wants nothing more than to take your head off. The famous Miami Massacre in which two mortally wounded villains took on and wounded and killed several agents of the FBI is a good example of this. Then again, a wounded villain could have caught a poorly aimed slug, and all the sudden has a vision of his mortality and throws in the towel right there on the spot. You never know. Don’t count on this… if you get it, great. But predicting psychology is a lot more guess work than predicting the weather.

Looking at these four ways of how a bullet stops a fight, I am left with the simple conclusion that the only thing that you can bank on is well aimed shots to the Center Of Mass. You want to use as big of a bullet as you can handle… in as powerful of a load as you can handle. You want to drive that slug deep into the vital organs of the threat. That has the best chances of stopping the threat via one of these 4 ways. Notice that I used the word “shots”?

I have never seen a situation where a shooting was warranted that only warranted one single shot. You can multiply your bullet’s “stopping power” by multiplying the number of hits. Follow that first shot with another one. Shoot until the threat stops. Firing one shot and waiting to see what happens is not a good idea. You shoot until the threat is no longer a threat. This is for Police or Military or Momma at the Mall in the parking lot. Banking on the One Shot Stop is a bad idea. The only people who do are the gun writers who get to deposit the check for the articles.

UPDATE:

To clarify and muddy the waters further, let’s look at what a round does specifically to tissue. Now, there are 2 different kinds of basic rounds. Handgun rounds and Rifle rounds.

Let’s look at Handguns first. Even the most powerful handguns fall far short of the energy levels of a rifle. This is why hunters don’t take to the field with handguns. A handgun bullet hits the target with and delivers blunt force trauma. Much like throwing a rock. The bullet penetrates because of its energy but this isn’t a piercing. A handgun bullet crushes the tissue all the way through and leaves the permanent wound channel as pretty much the only damaged tissue.

A rifle round is different. Thanks to the bullet shape and the higher energy levels the rifle bullet does much more damage. First of all, the rifle round pierces the tissue like a knife blade. It cuts through the flesh much cleaner than the blunt force of the handgun, but thanks to aerodynamic forces it does some nasty things. First off is the vacuum effect from the bullet’s aerodynamic drag. This vacuum pulls debris into the wound channel… debris that can become secondary projectiles and or introduce infection to the wound. (A handgun round will only punch a small bit of debris like a cookie cutter as it passes through barriers like fur or clothing) Very nasty that debris.

Now to understand what happens next, you have to have a little understanding of fluid dynamics. Have you ever watched a fast boat? What follows the boat? The wake. The wake is the essentially the boat’s slow motion shockwave of displacement of water across the surface as the boat passes through it. The same thing happens with a rifle round, but much much faster. Water can not be compressed. Water does react though… it’s pushed out and away, and then it is sucked back to fill the vacuum. Tissue is essentially water. Water that is held together in the collection of cells we call tissue. The shockwave from a rifle shot moves so fast and so hard that it literally shatters the cellular walls. The result is that in the area around the rifle hit, the tissue is pretty much transformed into jelly. The higher the power of the rifle the greater that cavitation damage. The shape of the rifle’s bullet of course also plays an effect, just like the shape of a boat’s hull. This shockwave can also disrupt the neural network through and around the body of the creature that has been shot.

There is some misunderstanding in the shooting community about this shockwave. It happens in a very small and ineffective way with a handgun round… yet because of this misunderstanding some guys play on it and sell handgun rounds that are advertised as creating huge shockwave damage which is just not possible. That would be like a Bi-Plane creating a sonic boom…. it just isn’t happening.

UPDATE:

5. Denial of Oxygen to the Brain. Cerebral Anoxia and Hypoxia.

Also contained herein: an addendum to CNS injury, some interesting facts about your heart and blood, and an extremely fun description of hydraulic cavitation.

Found these on the subject of Anoxia/Hypoxia and your heart:

http://www.thecochranfirmno.com/areas-brainjury-anoxic.html

http://healthlink.mcw.edu/article/921384224.html

http://hypertextbook.com/facts/2003/IradaMuslumova.shtml

I submit this as number 5 because it’s different from system-wide hydraulic failure. You aren’t necessarily bleeding the target out, or ever even inducing Hypovolemic or Hemorrhagic shock. The brain uses about a fifth of the body’s oxygen supply. Cut off or even restrict it, and he can die with most of his blood still in his veins and arteries. That’s what we hunters try to do with every big-game shot.

There are two—well, three main ways to accomplish this cerebral anoxia/hypoxia.

The third, which I almost didn’t mention, is to pinch off the carotid arteries. There’s one on either side of the neck, and if your grip is on target, the subject passes out in seconds. Cerebral anoxia. Denial of oxygen-bearing blood to the brain. If you continue to hold, he eventually dies. But the unconsciousness is, literally, seconds away. But that’s a hand-to-hand move. If you have a knife, you can stab him in his carotids, instead. This causes both anoxia and system-wide hydraulic failure (hypovolemic shock). Which one kills him first will be a toss-up, but he’ll loose consciousness in seconds. See, the carotids are two of the main branches of blood flow from the heart, so he’ll be pumping his blood directly out of his body. At the same time, that blood isn’t reaching his brain, so it’s dying of anoxia. He goes unconscious from the anoxia, and then that and hypovolemic shock are in a race to kill him.

Some facts:

The average adult contains about 5 liters of blood.
The average healthy heart, running an average 75bpm, pumps about 4 to 5 liters per minute.
That’s means the whole blood content of your body circulates completely just under once per minute.
Under stress or during exercise, the blood-flow can be quadrupled, to between 15 and 20 liters per minute.
A man in a fight, with his carotid artery cut, is, whether he likes it or not, going to be doing his darndest to pump out his own life’s blood as fast as he can. One minute, maybe two, to congestive heart failure, through just one hole in one carotid artery. A true spray.

Second, and far easier than an attack on the carotids is to is to simply shoot the man through the heart. This is what hunters try to do with big game. Destroy the heart, and it stops pumping. Blood flows for another second or so on momentum alone, and then it comes to rest, and even begins draining toward the lowest end of the body. Which is the opposite end from the head. Again, the brain needs continuous oxygen to function. All metabolic processes in the human body begin with ATP, and ATP is produced via the Krebs Cycle, which is essentially the controlled burning (oxidizing) of carbohydrates. No oxygen, no Krebs Cycle, no ATP, no cellular function, no brain function. Stopping the heart is the fastest kill possible, save for the destruction of the Medulla Oblongata. Stop the heart, and the subject will usually fall where he stands. Full death in seconds.

A note to your readers regarding CNS injuries: they will not stop the heart. That’s the other thing to be aware of regarding spinal shots. Even without nervous input, the heart will continue to beat, thanks to God’s miracle, the Sinus Node. The Sinus Node is a point at the top of the heart where an electrochemical impulse begins in the muscle cells, causing them to contract. The impulse cascades down heart from there, causing all the other cells to act likewise. Thump. The heart beats. The Sinus Node is not a thing, not visible or recognizable. It is just a place. No one, to my knowledge, knows exactly what makes it work. It generally does its thing on command from the CNS, but it will continue to generate its cascading signal even without that input. This is the grain of truth behind legends of hearts beating after being ripped out of bodies, as in “Temple of Doom.” The ramifications of this capability should be obvious. The heart is a trooper. It will keep fighting, even when all its comrades lie dead or dying around it. And it has won many Alamo-type situations, thanks to that fighting spirit. It might just keep you alive, all on its own, long enough for the paramedics to arrive. Or, it might keep your foe conscious just long enough to get off one last shot.

First, and easiest, is the lung-shot, which causes cerebral hypoxia. Hypoxia is Anoxia’s twin sister. Anoxia is the restriction of blood flow; hypoxia is free blood flow carrying restricted quantities of oxygen. The brain continues to pump blood to the brain, but the blood it pumps is oxygen-poor. Why? Because your target is drowning. You won’t know it, save for a little bubble or trickle of blood at his lips, perhaps, but his lung (or lungs, if you’re good) are filling up with his own blood, if those lungs even still exist. All the blood in the world won’t do you any good if it’s not carrying oxygen. As with a the carotid artery puncture, hydraulic failure is not far behind, for the lungs are by necessity one of the most bloody parts of the body, since surface-area is a major factor in transporting oxygen into the blood. Death from a lung shot, depending on severity, can be almost as quick as a heart shot. A rifle bullet or high-energy projectile of any sort can cause the lung to disintegrate via cavitation (see below), but even a simple hole in a lung will bleed hard and fast. Mid to high holes are better for this because they bleed down into the rest of the lung. It fills up with blood, which is just like filling up with water. An exploded lung will kill in seconds. A filling lung might take longer, but will still take only a fraction of the time required to actually bleed someone into Hypovolemic Shock with a liver shot or something of the sort.

All in all, it’s just another case for Center Mass. While a shot to the Medulla Oblongata is instant death, a shot to the heart is almost as fast—indeed, just as fast, in practical terms. Lungs are close behind. A good side-on with a rifle will pass through one lung, through the heart, and through the other lung before exiting. Any one of those brings near-instant unconsciousness, if not near-instant brain death. So, yeah, aim for his heart. “Aim small, miss small,” goes the “Patriot” quote. Aim at the heart, and if you miss, you hit the lungs. Any of them will cause cerebral anoxia/hypoxia and almost instant incapacitation.

I mentioned “cavitation” above. In the interests of general education and the dissemination of information, I’ll give it a few words as well. What I’m referring to is specifically “Hydraulic Cavitation,”

First, Newtonian physics: A moving mass hits a relatively (it’s ALL relative, after all) stationary mass. The stationary mass is, of course, happy where it is, thanks to Inertia (God rest ye, Newton). However, the moving mass has momentum, another kind of Inertia, and insists that the stationary mass “Get out of the way!” Well, for the stationary mass to vacate, it must acquire some kinetic energy. It gets this energy from the object that is striking it. The amount of energy transferred depends on the masses involved, as well as some variables such as elasticity and friction, and of course the actual amount of energy the moving mass starts with. Basically, it takes more energy to move a bigger object. So if the stationary mass is huge and the moving mass is tiny, the stationary mass will “stop” the moving mass. Splat. Like a meteor hitting the earth. Of course, nothing is absolute. The stationary mass will move a little, but in the case of the meteor and the earth, the difference in the earth’s velocity isn’t enough to notice. If on the other hand, the moving mass is huge and the stationary mass is tiny, the moving mass may not even slow down to a noticeable degree, but the stationary mass will suddenly take on a great deal of velocity. You’ll see this if you ever see someone (a person, a deer, a dog) get hit by a car. The car hardly seems to notice. But the poor victim notices. The victim does NOT plaster to the front of the car. Rather, the victim launches, suddenly taking on a velocity even greater than car had when it hit. Hence the “flying thirty feet through the air” part of most car-vs-pedestrian encounters.

Yeah, anyway, hope you followed that.

So, bullet vs you. Bullet hits your flesh. Your flesh would rather sit still, but the bullet is very insistent. “Incoming fire has the right of way,” is another quote on M. Ogre’s site. So after a brief (read: instantaneous) resistance, the flesh at the point of contact gives way. No, I take that back: it FLIES away. But the bullet is fast, man. Real fast. And soft tissue (brain, guts, and the like—all 70+% water) isn’t much of a resisting force. So the bullet and the leading edge of the shock-wave it created on impact travel together through the body. The shockwave trails out in a wide cone behind the projectile (like the fire coming off the nose of an Orbiter on reentry). But wait, that shock-wave-cone-thing is the actual tissue from the point of impact, still moving away from the bullet. So what about the other tissue it hits along the way? Well, the tissue compresses as much as it can. But tissue is, again, seventy-something percent water. Water is liquid. Liquid is a “compressed state.” Unlike a gas, a liquid is a small as it can get, molecularly speaking. The molecules simply can’t get any closer together, unless you’re measuring on a minute scale and super-cooling the liquid. Which we’re not. In fact, we’re heating the liquid. Because what energy the bullet imparted to the flesh that couldn’t be immediately turned into motion was turned into heat instead. And the bullet is hot to begin with, because it was propelled by an explosion. So that’s just one other factor AGAINST compression of the tissue.

So where does this flesh, being bulldozed as it is by other flesh, go? Well, find a man who’s been shot in the front, and take a look at his back, and then you tell me. That cantaloupe-sized hole is there for a reason.

Okay, so we have a cone-shaped bulldozing effect. But if that’s the original flesh from the point of impact, pushing outward, then what’s inside the cone? Nothing. It’s empty. There isn’t even any air there. The bullet is moving too fast for air molecules to stay filled in behind it. See, they had their own inertia. Then the bullet came whipping through, pushing them away to the side rather harshly. The air molecules are still moving OUT after the bullet passes. It takes them a moment to slow down and reverse course, to fill in where the bullet went through. Same with slightly-compressed soft tissue. That original mass of flesh is slowing down, because it’s running into all of the other flesh in the affected area and transferring its energy. So the shockwave is now no longer pushing like a bulldozer, but passing from cell to cell like a true wave. Like a seismic wave travels through the ocean. But fear not, you still get your explosive exit wound. After all, that seismic wave ends in a tsunami when it hits the shore, even if those water molecules aren’t the same ones it started in. So, yeah, that original mass of flesh is slowing down, but it hasn’t stopped yet, and it certainly hasn’t reversed course to fill in the hole. But it’s about to.

You see, that flesh is feeling a pull from behind. This can be compared to the blow-back in a high-heat explosion. Remember those images of early nuke tests? The initial shockwave goes by, and then the wind starts blowing TOWARD the epicenter, because the heat at the center has caused the air there to shoot up into a mushroom cloud, leaving a void that has to be filled. Well, in the case of your bullet, the shockwave itself caused the void.

Ladies and gentlemen, that void is what we officially call the Cavity. Hence “Cavitation.” The Cavity is a vacuum, and nature abhors a vacuum, so it tries to fill this vacuum with whatever is nearby. Air flows in from the entry-wound, but most of all, soft tissue, having offloaded the kinetic energy of the shockwave to the next layer of cells, falls back into its original place. Except it doesn’t fall, it surges. This in itself can happen with an almost explosive force, causing a little bit of spray forward, toward the entry wound, and adding to the explosion that’s currently taking place at the point of exit.

So what is the final effect of all this? Well, the flesh of your brain just vacated a volume the size of a plum (or even larger) and then refilled it, in a tiny fraction of a second, probably at supersonic speeds. Complex molecular structures such as those that form cells simply can not stand up to this kind of abuse. The bonds that hold cells to each other to form coherent tissues are even weaker. The result is that what flows back into the gap—as well as all soft tissue anywhere nearby that got pounded and compressed and generally abused by the passing shock-wave—is no longer tissue at all, but rather what those in the business call “soup.” It’s just assorted liquids, with a few bits of tattered, barely coherent flesh suspended within.

My 6mm did this to one entire lung of a Tennessee whitetail deer. I found some of that lung along the blood trail, mixed in with the blood itself. There were a few recognizable chunks, but the rest of the lung tissue was completely pulverized. A high-energy bullet to the head will destroy most of the brain in the same way.

What does this mean for you shooters? Well, it means “If you can choose what to bring to a gun fight, bring a rifle, and bring friends with rifles.” Pistols rarely deliver enough energy to cause cavitation. You can shoot a man in the head, and he just might live, all though he might be a changed man afterwards, either because of the psychological trauma or because you remapped the synapses that determine his personality (yes, your personality IS a mapping of synaptic links across the brain). All you’ve done is make a hole. However, shoot a man in the head with a rifle cartridge (even a 5.56 NATO Ball, if the range is under a hundred yards or so, though bigger holes are still better holes), and you’ve made a soup out of everything inside his skull.

Indeed, Cavitation is one of the main reasons why Michael Lee Platt was able to kill as many FBI officers as he did on April 11th of 1986 after already taking a supposedly mortal bullet wound in his chest. The FBI were using pistols. Platt had a Mini-14. Cavitation is the reason rifles stop the target when pistols can’t. Cavitation and the fact that rifle bullets go through Kevlar on a regular basis. If you want to stop a rifle bullet, you have to try harder.

Special thanks to Horde Member Ancient for this new information.