What is "Knock Down Power"

Strictly speaking, if a person or animal drops virtually instantly from being shot, that could be considered "knock down power," as long as we don't require "knock down" to included being blown off your feet and landing six feet away. In any event, we have to agree that it was the bullet that did whatever damage that occurred.

Fairbairn describes in his book how he consented to standing behind a bullet proof shield, just for the experience. Although he did admit that the experience was something else, he reported, if I remember correctly, that the impact of the bullet was relatively slight. In that sense, a bullet from a handgun could not be capable of true knock down (or knock over) power. However, I'm going to be the last man in line if there's ever going to be a test of soft body armor. I don't want to prove that I can't be knocked down.
 
Well, then, is "stopping power" the same as "knockdown power" or not?
Click to expand...

They are exactly the same in the sense that both of them are ambiguous terms comprised of ambiguous definitions based on subjective assessment.

Here is a classic video that demonstrates the amazing power of "knock down" power when a person wearing a rifle rated vest stopping a .308 at VERY CLOSE range.

http://www.liveleak.com/view?i=310_1212367354

And surprise surprise, the tall guy in the video mentions being stuck with a pin and noting it isn't the power of the pin sticking you that causes you to jump, but your reaction to it.

Some people like to argue that this video proves knockdown power as you see the soldier go down. If you watch carefully, his knees crumple. He isn't knocked down but instead reacts to the bullet impact by dropping and twisting as he goes down. http://www.youtube.com/watch?v=EV0pN-LaW6E
 
Last edited:
Knock down power. AKA can of worms on a forum like this!
Just think about what that Newton guy had to say a long tome ago. You know, about equal and opposite reaction! If a firearm shot a projectile with enough force to knock a man off his feet, the equal and opposite force would knock the shooter off his feet as well. Have you ever fired a gun that knocked you off your feet?
 
Think of knock-down as the Tooth Fairy of the firearms world: lots of people tell you it's there but no one has ever seen it. Except in movies, of course, where Mr Bad Guy flies up and backwards about 5' when he gets shot. And Tinkerbell lives in the lantern in Peter Pan's hideout. But other than that, no one has ever really seen it.

Too bad that Newton guy made up a Law so that no one could make the bad guys fly through the air when shot, that would be cool.

There have been so many "formulas" made up and promoted trying to quantify and measure "knock down power" that most people have made up their own or just regurgitate what they have read somewhere.
 
All

I know it sounds corny, but Mythbusters actually busted this Myth. It's something akin to pulling a tablecloth out from under all the dishes on the table. The bullet is simply moving too fast and is too light for enough kenetic energy to transfer to a heavy target.

They proved this by shooting a number of different firearms at a dead pig that was barely hanging by a hook. They then measured how much the pig moved whe the bullet hit. They never actually got the pig to move.

As previously stated in this thread, the "knock down power" of most guns is actually caused from the "oh crap I'm shot" effect or from damage to organs/nerves by the bullet.

Again, sorry for the Mythbuster reference, but they use scientific methods to get results not the speculation of what we believe to be true.:rolleyes:
 
swinokur said:
How do we know the difference between an near instantaneous CNS collapse and a possible collapse from just the force of a bullet?

I don't have a working knowledge of physics but what is a real world comparison to a 180 grain bullet striking a 220 pound man at 1000 FPS?
Click to expand...


1) You know because of where the bullet hits and the damage that it does. We can remove the potential for CNS damage by examining the effects of a bullet that is stopped by body armor. Many, many people over the course of decades have been shot while wearing body armor and shot by every conceivable cartridge from 22LR to 50BMG and 12ga. The general consensus is that it typically hurts like hell and definitely does not knock you down.

2)Since "knock down" is a consequence of momentum and not kinetic energy, the two variables of weight and velocity can be swapped or changed by an equal and off-setting amount and you'd get the exact same results.
For example:

A 180gr bullet at 1000fps would have the exact same "knockdown power" as a 1800gr bullet going 100fps. Or, as an example, a MLB baseball weighs an average of 5 1/8 ounces, which is 2242gr. That is 12.45 times the mass of the your 180gr, so it would have the same momentum at (1000/12.45) 80.32fps. 80.32 fps is 54.76 mph.

So, your 180gr bullet at 1000fps has the same "knock down power" as a baseball thrown by a 5th grader.

Even at 2000fps, your bullet has the same "knock down power" as a baseball at 100mph. Does a fastball "knock down" a major league batter? No. It does not.
 
I'll bet there's a couple of people around here that got knocked down when they fired their first shotgun when they were a kid. And maybe even a couple when they fired their first shot from a .454 magnum revolver.

Shooting into animal carcasses was all that was done in the Thompson-LaGarde (if I'm remembering that correctly) tests a long time ago and pretty much the same thing was done even earlier, supposedly, when the New York City Police decided to adopt a standard revolver, which resulted in a .32 being adopted. I guess they used smaller animals that time.

I once saw a bull shot with a shotgun, an uncommon weapon used for killing an animal for butchering for sure. I wouldn't say it was knocked off its feet but it certainly went down almost instantly. Mind you, that happened close to 50 years ago and I can't honestly say I remember every little detail.
 
BlueTrain said:
I once saw a bull shot with a shotgun, an uncommon weapon used for killing an animal for butchering for sure. I wouldn't say it was knocked off its feet but it certainly went down almost instantly. Mind you, that happened close to 50 years ago and I can't honestly say I remember every little detail.
Click to expand...


Actually, most of NY state has been shotgun only deer hunting for decades. In fact, every deer that I've ever seen killed with a gun has been killed with shotgun slugs.

Yes, there have been deer that fell immediately on the shot. It's not even that uncommon. On the flip side, I've seen more, far more, than flinch like they got stung by a bee and then run away like nothing happened, only to drop in a pile 50 or 100 yards later.

I've seen large bucks drop like they got hit by a truck and I've seen 60 pound fawns run like they weren't even injured.
 
Fall down is NOT the same as 'knock down.'

Mr Newton's gravity works very well.
Click to expand...

Just so. Animals depend on their neuro-muscular systems working properly to remain standing. If you disrupt either or both with a bullet, the animal falls down. It hasn't been knocked down. The Mythbusters episode (which, frankly, should have put an end to this controversy once and for all) used inanimate objects that (obviously) didn't need to be doing anything actively to maintain their upright posture, and they couldn't knock them down even with some pretty impressive weaponry.
 
Fall down, knock down, it dont really matter as long as they end up on the down side of things :) that deer was tasty too.
 
Many thanks for all the well thought out replies.

Most of which confirmed what I thought to be
correct, I just didn't have the science to back
it up.

Seems to me the best way to knock someone
down in a defensive situation might be to get
all "Walking Tall" on them and use a really big
stick LOL.

Again many thanks, Jim
 
"Knock down power"

http://www.youtube.com/watch?v=ShE2r...layer_embedded
Click to expand...

Another fine video of a creature being shot that falls down and is not knocked down.

How do we know the difference between an near instantaneous CNS collapse and a possible collapse from just the force of a bullet?

I don't have a working knowledge of physics but what is a real world comparison to a 180 grain bullet striking a 220 pound man at 1000 FPS?
Click to expand...

CNS disruption and falling and force of a bullet and collapsing are the same thing. CNS is being disrupted. The force of the bullet, however, isn't knocking down the critter.

Look at the video of the warthog. He wasn't shot from above by a parachuting hunter, but from the side. Which way did the hog fall? Almost straight down. If knock down power was at work here, the shot from the side should have toppled the warthog over on its side instead of causing his legs to collapse underneath him. The warthog fell down as a result of disruption to the nervous system causing a loss of control of his legs.

Fall down, knock down, it dont really matter as long as they end up on the down side of things
Click to expand...

Knock down power is often associated with the notion of taking somebody out of a fight, but that isn't what it is. I think some time back, people realized that the "knock down" aspect often did not neutralize the threat who was down, but not stopped, hence the notion of stopping power and another can of worms.
 
Last edited:
Bladed weapons have not been in general use for for over a century now, so it has been forgotten the awesome “stopping power” these things had.

I purchased and read two books titled “Sword Fighters of British India” and Sword fighters of the British Empire”

http://www.amazon.com/Sword-Fighter...=sr_1_1?s=books&ie=UTF8&qid=1289055187&sr=1-1

http://www.amazon.com/Sword-Fighter...=sr_1_2?s=books&ie=UTF8&qid=1289055187&sr=1-2

There are plenty of examples of arms, legs, heads being chopped off, along with a few accounts of standard British service models completely cutting people in two!.

That is stopping power.

There are accounts of opponents being so close that the swordsman decided to punch the opponent with the guard. The construction is stout enough to crack a skull and there are accounts of instant kills.

Firearms had the reach advantage, but in terms of stopping power, they were second best.

M1885BritSwordandScabbardview.jpg
 
Likely the sheep weighed about the same as a grown man, too. So in that one case, a given rifle cartridge literally knocked down a sheep.
Click to expand...

No it didn't.

The sheeps reaction to the trauma caused by the bullet caused the sheep to jump and fall. Similar effects can be achieved through fright alone on both human's and animals. Or electrical shock, or..............oh, never mind, I guess this issue will never be resolved.

If the dang recoil didn't knock the shooter off his feet, then the bullet didn't knock the sheep off it's feet.:cool:

I know of an instance where a friend snuck up on some does feeding in a field near a small town in California along the Nevada border. The deer were some what used to humans so they weren't especially alert. He approached the deer from behind and touched one with his fly rod to "count coup" as he put it. The deer was scared so bad it jumped high in the air, peed all over him:D, fell down, got up and ran like hell.

The way the tip of that rod knocked down that deer was just awesome.:cool:

If bullets knocked people down, they'd go sideways or backwards ala Hollywood. Not drop straight down, as is the case in real life.:cool:

Of course, if a person is already off balance, they can be knocked off their feet by a bullet----or by a push from my hand, for that matter.
 
Last edited:
You must log in or register to reply here.
Back
Top