Knock down/stopping power... Fact or Fiction?
- Thread starter TheRaskalKing
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I don't understand why people don't believe there is such a thing as knockdown power. I guess they've never been knocked down! Likewise, it shouldn't take a genius to know that the firearm will absorb most and sometimes all of the recoil of the shot while the bullet goes on to do its work. Didn't anyone ever see a boxer knocked down by another boxer?
I agree that stopping power is a slightly different concept but it doesn't negate "knockdown power." Here I do not use the expression to mean knocked backwards for a few yards, like you see it in the movies. That would only happen if you were hit by a car.
I likewise don't understand how anyone can say a deer is not knocked donw. Let me explain. You can shoot a deer (or a human) in the head and they will go down. That's all I mean by knockdown power. Will they get up again? Probably and probably right away, too. What they do then is another issue. A deer will probaby run fifty or a hundred yard and stop and look back at you. Some humans will start running and won't stop until they reach home (or the hospital). But they were knocked down for sure.
The problem here is that no outcome is guaranteed, merely possible. If you want to say, on the other hand, that someone hit hard enough in the head just collapses and isn't knocked down, well, that's OK. I'll not argue.
My advice is to duck.
I agree that stopping power is a slightly different concept but it doesn't negate "knockdown power." Here I do not use the expression to mean knocked backwards for a few yards, like you see it in the movies. That would only happen if you were hit by a car.
I likewise don't understand how anyone can say a deer is not knocked donw. Let me explain. You can shoot a deer (or a human) in the head and they will go down. That's all I mean by knockdown power. Will they get up again? Probably and probably right away, too. What they do then is another issue. A deer will probaby run fifty or a hundred yard and stop and look back at you. Some humans will start running and won't stop until they reach home (or the hospital). But they were knocked down for sure.
The problem here is that no outcome is guaranteed, merely possible. If you want to say, on the other hand, that someone hit hard enough in the head just collapses and isn't knocked down, well, that's OK. I'll not argue.
My advice is to duck.
lee n. field
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It's rhetoric. Marketing. Which doesn't make it either fact or fiction.
The target gets "knocked down" as a consequence of damage, not physics. An armored target might well absorb the force, and remain standing.
Darren Roberts
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I believe the intended use of the term Knock Down power is, will the impact of the projectile have enough energy to actually knock someone down.
This is assume that there is no penetration, no injury that would cause someone to "drop". Just straight forward force vs resistance. In this scenario, knock down power is a myth.
Now if you add the parameter of penetration and injury then your argument takes a down hill turn. The fact that a bulet is able to pass through a body reduces the force of impact, therefor decreasing the likelyhood or possibility of a true knock down.
People falling straight down from injury is not the same as knocking someone down.
Crow Hunter
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There is no such thing as "stopping power" or "knock down power".
They are inventions for variable physiological phenomena created by people with a weak grasp of basic Newtonian physics to explain the reactions of humans to being shot.
However, there is such a thing as "operator effectiveness".
This effectiveness is related to the efficiency of converting stored chemical energy into directed kinetic energy that disrupts key components critical to the functioning of a target.
This is the same whether you are talking about a human or a tank or an airplane.
The difference is that with materiel targets, MINDSET isn't a factor.
They are inventions for variable physiological phenomena created by people with a weak grasp of basic Newtonian physics to explain the reactions of humans to being shot.
However, there is such a thing as "operator effectiveness".
This effectiveness is related to the efficiency of converting stored chemical energy into directed kinetic energy that disrupts key components critical to the functioning of a target.
This is the same whether you are talking about a human or a tank or an airplane.
The difference is that with materiel targets, MINDSET isn't a factor.
You're going to have to be more specific and descriptive.
I've knocked down plenty of people without being knocked down myself. Just because I generate enough force with my hands, my fist or my shoulder to knock another to the ground doesn't mean that I wind up on the ground myself. I do realize that there is an actual Newtons law of conservation of energy (I think that's the one that applies here) but I've never understood why people cite it as evidence against knockdown power when it is clearly possible to knock someone down without getting knocked down yourself.
So, physicists, please explain why I can use my shoulder to send someone flying while remaining upright myself but the massive ++++P slug from my huge caliber handgun can't knock someone down without sending me flying too.
Then we can make a sticky out of it.
Glenn E. Meyer
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There is not enough physical force in handgun or most rifle (that you can carry) rounds to knock you down. There is NO argument about that.
As far as handgun ammo - the consensus among experts and pro users that between modern 9mm, 40, 45ACP there is little functional difference in utility.
The argument is really over.
As far as handgun ammo - the consensus among experts and pro users that between modern 9mm, 40, 45ACP there is little functional difference in utility.
The argument is really over.
I don't think anyone actually believes that any gun will actually knock someone down. Accurate or not the term "knock down power" has morphed into a term used to describe how effective one round is in comparison to another. I think it is silly to even argue the point when everyone already knows a gun won't actually knock someone down.
While there are lots of overlap and with most of the common handgun rounds they all work about the same. But on the extreme ends of the spectrum it is undenieable that some rounds are more effective than others. Even within the most common rounds some loadings and bullet types are more effective than others.
While the term "knockdown power" may well be technically incorrect, most of us should understand what someone means. If someone wants to coin a better term, then I'm all for it.
Cheapshooter
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You would be surprised! I heard one of the "expert" gun counter clerks at a BPS telling someone what they really needed instead of a 9MM was a 45 because "You'd knock somebody down even if you just hit him in the hand" I heard a similar comment by an ammo dealer at a gun show. So, there out they're out there, and they are spreading the word to anyone willing to listen!
How about incapacitation?
m&p45acp10+1
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Knock down power, and stopping power to me are a bit mythical. It is not like the movies show. I know from first hand experiece of being shot. I took a load of 12 ga hibrass number 6 copper plated from a turkey load. Out of an 18 inch barrel from less than 6 feet. Big news flash here it did not knock me down. It did spin me a small bit, though not that much. It did tear a huge wound. I quite nearl died that night. It took a team of top tier surgeons to piece me back together. I was in top notch physical condition, and an acomplised athaleet at the time.
There are more variables than can be factored in a gun shot wound.
Ballistic energy numbers, penetration, critical hits, and many other things play a part. Though a person that is mortaly wounded can still fight back defying common logic. See the FBI Miami shoot out report. One of the shooters was literaly walking dead. He still managed to kill a couple of people.
There are more variables than can be factored in a gun shot wound.
Ballistic energy numbers, penetration, critical hits, and many other things play a part. Though a person that is mortaly wounded can still fight back defying common logic. See the FBI Miami shoot out report. One of the shooters was literaly walking dead. He still managed to kill a couple of people.
I believe knockdown power does exist, but you have to stop the bullet from penetrating through and absorb all of the energy. That means wearing a bullet proof vest. Will 1,600 ft lbs of energy from a 44 mag knock someone down wearing a vest that stops penetration? I don't know, maybe. I'd bet 3,000 ft lbs from a Brenneke Black Magic would knock almost anyone to the ground that is wearing a vest to stop it. Thats why I have slugs following the buckshot in my HD shotgun, for body armor.
Crow Hunter
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Inertia.
You are an object in motion. When you hit something stationary, a portion of your inertia is imparted into the person who you hit. If that person weighs less than you and you have more inertia, they will move and you will slow down.
If you are a 105lb girl and you run into a 300 lb linebacker, even if he isn't expecting it, your inertia won't be enough to overcome his inertia and you will bounce off.
This can be demonstrated (to great amusement) by dropping a basketball and a tennis ball together with the tennis ball on top. When they both stop because they hit the floor and bounce off, the basketball will impart inertia to the tennis ball. The tennis ball will shoot back to the ceiling even though it was only dropped to the floor from waist high. Because it picked up some of the basket balls inertia.
You are hitting with more inertia than a bullet is. Bullets themselves don't have much inertia, they kill based on penetration. (That is why "bullet proof" vests work, you can't penetrate the fibers)
The bullet can't have more force going forward than it did pushing backwards against your hand. If it had enough energy to take a person off their feet, it would take the shooter off their feet as well.
"Knockdown" in both hand to hand combat and ballistics is more of a physiological effect, than a physical effect. Someone punching you in the face may cause you to drop because your central nervous system was shocked by a "knockout punch" or because you torqued the person over because the force of the blow cause them to lose their balance.
There is alot more too this, but this is the best I can do without a chalkboard.
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Glenn E. Meyer
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Jonathan Z - you are incorrect. All of that has been tested and the footpound numbers are not relevant. Folks fall down because of the effects of the round on CNS and circulatory system - NOT the energy displacing them in space.
In fact, people shot usually fall forward - how about that - that's the way the body crumples when you lose motor control.
If folks don't really understand the physics and physiology - please spare us the cliches.
The issue is whether a round has the ability to impact CNS or circulation for the most part (separating out various psychological effects). Whether the configuration of a round has these properties is under debate and research.
Thus, unless the Yamato lands one on you, it's not knockdown. In fact, I know of a case where a guy took an 11 inch battleship round in his head.
His head disappeared and the body stood there for a bit spurting blood.
Folks take numerous shotgun rounds, 223s, handgun rounds and then run around for a bit.
So can we cut the crappola?
In fact, people shot usually fall forward - how about that - that's the way the body crumples when you lose motor control.
If folks don't really understand the physics and physiology - please spare us the cliches.
The issue is whether a round has the ability to impact CNS or circulation for the most part (separating out various psychological effects). Whether the configuration of a round has these properties is under debate and research.
Thus, unless the Yamato lands one on you, it's not knockdown. In fact, I know of a case where a guy took an 11 inch battleship round in his head.
His head disappeared and the body stood there for a bit spurting blood.
Folks take numerous shotgun rounds, 223s, handgun rounds and then run around for a bit.
So can we cut the crappola?
Crow Hunters response is a very good explanation of something that is hard to explain. Something like that should be taken and made into a sticky so people can find it themselves, or be pointed there when the cliches start.
There are all kinds of truth's in life that seem on the surface to fly in the face of common sense. Usually the reason they seem unreasonable is that you are forgetting to think about some part of the equation that has a big impact. Knockdown power is one of those.
kinetic energy does not equal inertia. Inertia is momentum and momentun is all you have to stop. the kinetic energy will be changed into heat energy and for the record 3000 ft.lbs is enough to raise your body temprature about .000001 degrees.
As for your inertia a 240gr 44mag at 1400fps has about the same inertia as a 95 mph fast ball, your slug is about that of a pro quarterback's frozen rope throw.
As for service rounds and "knock down" a 124gr 9mm has about the same momentum of a baseball going a scorching 40 mph.
And that's about all you'll feel wearing a vest.
As to arguing "stopping power" most of it is dancing on the head of a pin.
there's no accounting for instant incapisation with a com shot because without CNS damage no amount of damage to the cardio vascular system can reliably cause instant incapisation. Even with full cardiac arrest the brain and body can still function for 15 seconds enough time for Mr BG to shoot to slide lock.
Carry what you want, If you really want an edge in stopping Mr BG from doing you harm practice failure to stop drills.
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Kreyzhorse
New member
That was a good point earlier. I've shot several deer with a .308, 7mm Rem Mag and a 45-70 Gov't and have never knocked one down.
I really don't believe that stopping power / knock down power exists in a hand gun. Proper shot placement of course does exist.
I really don't believe that stopping power / knock down power exists in a hand gun. Proper shot placement of course does exist.
Therealkoop
New member
It doesnt matter if the handgun recoiling or the action moving absorbs force. There simply isnt enough physical energy to know a person down irregardless. its math and physics, and its pretty impossible to show otherwise.
I had a group of guys telling me that the .45 acp was developed in WWI so that if a man was jumping down into a trench with a knife, you could aim up and shoot him, and the .45 would reverse his motion and throw him back out before he stabbed you.
Yup.
I had a group of guys telling me that the .45 acp was developed in WWI so that if a man was jumping down into a trench with a knife, you could aim up and shoot him, and the .45 would reverse his motion and throw him back out before he stabbed you.
Yup.
I think that we could better advance our discussions about choosing defensive handgun cartridges if we all dropped the terms "knockdown power" and "stopping power". Those terms are too imprecise, and even misleading.
What we need to do is recognize what we are seeking a defensive handgun bullet to do. Most incapacitation is accomplished by loss of blood pressure.
So we should discuss incapacitation power or perhaps come up with an incapacitation index. I know that there was a Relative Incapacitation Index (RII) promulgated in the 1970s or 1980 which promoted fast light handgun bullets.
For defensive handgun cartridges, shot placement is always important. Remember that shot placement must be considered in all three dimensions because we are contemplating three dimensional threats, not paper.
You want a bullet that will create the largest volume of crushed vascular tissue to cause the greatest loss of blood in the shortest time period. Part of the volume equation is depth which requires some reasonable penetration under all circumstances you are likely to encounter.
Temporary cavity is irrelevant for defensive handgun cartridge bullets which travel between 800 - 1500 fps. Testing has demonstrates that bullets traveling under 1800 - 2000 fps do not cause damage to vascular tissue with the temporary cavity, with the exception of the liver.
What we need to do is recognize what we are seeking a defensive handgun bullet to do. Most incapacitation is accomplished by loss of blood pressure.
So we should discuss incapacitation power or perhaps come up with an incapacitation index. I know that there was a Relative Incapacitation Index (RII) promulgated in the 1970s or 1980 which promoted fast light handgun bullets.
For defensive handgun cartridges, shot placement is always important. Remember that shot placement must be considered in all three dimensions because we are contemplating three dimensional threats, not paper.
You want a bullet that will create the largest volume of crushed vascular tissue to cause the greatest loss of blood in the shortest time period. Part of the volume equation is depth which requires some reasonable penetration under all circumstances you are likely to encounter.
Temporary cavity is irrelevant for defensive handgun cartridge bullets which travel between 800 - 1500 fps. Testing has demonstrates that bullets traveling under 1800 - 2000 fps do not cause damage to vascular tissue with the temporary cavity, with the exception of the liver.
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