What is "Knock Down Power"

It's not a bullet weight to body weight ratio, it's more complicated than that.

When you get into massive trauma to an unsuspecting animal the results are often more spectacular than one might expect. Rifle bullets can really tear up a lot of tissue compared to handgun bullets. Unlike pistol bullets that create temporary cavities that typically rebound leaving only bruising, high powered rifle bullets can create large impact cavities that literally tear tissue apart and severely traumatize adjacent nerves and organs.

The animal still isn't "knocked down" but it may go down instantly at the shot due to the shutdown of major organs and other trauma.

Here's some interesting reading.
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^^^
Also you have to keep in mind most 4 legged critters anatomy, proper shot placement from the side will penetrate BOTH lungs & possibly even the heart. The animal is again, also unsuspecting - not hyped up on drugs, or adrenaline, and isn't in fight or flight mode. I remember one of the russian boars I shot with a .308 blasted lung tissue all over the log behind it - after field dressing it and bring it back to the lodge & the butcher starting on the meat, the lungs were pretty much destroyed. The boar after being shot tried to take 1 step to run, wobbled and fell on its side. It didn't instantly die, but it did die pretty quickly.

On this same trip, one of the other guys wanted to hunt his boar with a pistol - I forget the caliber but it was a large revolver with 6" barrel, not sure of the rounds being used either but it took multiple hits on his boar to bring it down due to lack of penetration. Recalling the wounds, I almost am willing to bet they were using some sort of hollowpoint - one specific shot on the shoulder looked like someone had taken an ice cream scoop and removed a chunk of muscle there. No more than 5" penetration though on a lot of the shots due to the dense muscle.

When it comes to 9mm vs 45, if you look at side by side ballistic gellatin tests comparing 9mm, 40, .357 sig, 45 using modern defense rounds - the temp cavity and penetration is almost the same for all of them. Stopping power for each is also similar, shot placement is king. Handgun rounds don't reach the velocities needed for the tissue affected by the temp cavity to tear from the shock of the bullet passing through, but rifles do this. Tissue is elastic, and it takes a very high velocity round for it to cause this - that from a rifle.

What it all comes down to? Pick the caliber & gun you are most proficient with/accurate with. Train with it a lot, if you ever have to use it -at the end of the day whats going to matter is where you hit with it and not the caliber, or whether it was a tricked out 1911 or just a stock glock.
 
I'm betting a 4 bore elephant gun would knock you down. Anyone willing to experiment;)

Basically a bullet is too small and fast to exert the kind of leverage necessary to knock a person down. A football linebacker has less energy than a .44. He is able to knock down a quarterback because of the way his energy is applied.
 
A football linebacker has less energy than a .44. He is able to knock down a quarterback because of the way his energy is applied.
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That's momentum.

A linebacker has more momentum that a bullet. A lot more.

A 300 pound man going 15 miles per hour has 912kilogram-meter/second momentum

An 800gr 50 BMG bullet going 2895 fps has just 45 kilogram-meter/second momentum.

The linebacker (not even running super fast) hits with more than 20 times as much "effect' as even some of the most high powered rifles.

Kinetic energy produces hydrostatic shock, if there is any, but it does not produce "Knock down power", if there is any. "Knock down" comes from momentum.

Kinetic energy can be dissipated in many ways. Momentum can not. Momentum is transfered and conserved, period.
 
In terms of "momentum", the time that it takes to apply the momentum makes no difference in mathematical terms.
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Mathematics says that the recoil of the 12 ga. pump and auto loader are the same. My shoulder says they aren't, since the latter is spread over more time.

We're making this too complicated. Bullets don't really knock people down, but the reaction to the bullet may. The momentum of a bullet can "knock down" a person who's off balance, just as recoil can knock over a shooter who's off balance, or at least cause them to further lose their balance and fall over. What waterfowl hunter hasn't seen, or had this happen?

I'm not saying just who it was fell over, mind you. :D
 
Last deer I shot was knocked down, he was in mid air tho when the shotgun slug hit him :) so in all reality he fell as when the slug hit he couldnt run anymore :) and dropped right there. Shot another was running right at me, hit him in the neck and turned him around 180 was it his reaction or the slugs power he was like 20 ft away. I get real close :) whatever it is called, he stopped and dropped right there.
 
If you've ever been knocked down by anything, you should believe that there is such a thing as knockdown power.
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I have seen major league batters "knocked down" by wild pitches that barely connected with them. Oddly, I have seen major league batters "knocked down" by pitches that did not connect with them.

I saw a kid shot in the face with a Nerf ball (the soft spongy foam type) that was "knocked down."

I have seen pepper spray "knock down" a large man.

There is such a thing as knockdown power. I have been hit by a car and knocked down. In fact, it hit me, tossed me through the air for some distance before I reconnected with the pavement in an uncontrolled manner.

I don't think a lot of people understand the difference between being knocked down and falling down.
 
Nnobby45 said:
Mathematics says that the recoil of the 12 ga. pump and auto loader are the same. My shoulder says they aren't, since the latter is spread over more time.
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Yep, that's because we're talking about yet another factor.... not Kinetic Energy, not Momentum.... but "force".

The applied force is based on the acceleration rate. The slower the acceleration is applied, the less "force".

A 12ga applies the recoil more slowly than does a rifle. The 12ga has more momentum (most likely), while the rifle has more kinetic energy.

High kinetic energy, low momentum and rapid acceleration.... like a 204Ruger for example.... equals low recoil.


Long story short, equal momentum, applied at a faster rate, hurts more than equal momentum applied at a slower rate.
 
I'm not sure how to quantify "knock down power"

But I don know that good tequila has more "knock down power" than good beer. That's why I stick to good beer.:D
 
quote" If someone is sitting in a chair and you stick them in the rear with a very low velocity and low weight pin they will jump up. I can find no term for this." end quote

That, sir, is called "knock up power." :D
 
Usually these discussions focus on how if a bullet would knock down the target, it would knock down the shooter. Perhaps but that gets into a discussion of "kick." Yet the fact remains that a person or an animal can be knocked down by application of force, be it a bullet or a blow from an object or I suppose even the wind. It doesn't matter how it happens, only that it can. It doesn't matter that it can't be guaranteed, either, even with the .45 ACP.

The subject has come up before, you know, decades ago, when people were already shooting at one another. But one writer from before WWII said the more he studied the matter and the more he learned about it, the less certain he was about it. Apparently that is still true.

There is one photo I've seen, which I'm unable to reproduce or give a reference to, of a soldier in the Spanish Civil War who had been shot. It looks like he was advancing but he was caught by the camera in almost a posed position with his arms outstretched on either side, one hand holding his rifle, I think, his head back, and probably about to fall backward. It certainly looks like an instant stop and maybe even a knockdown. It almost looks like a Hollywood scene.

So it a knockdown possible? I'd have to say yes and besides, I keep remembering how my father said that if a .45 hit you in your little finger....
 
I once saw a boy get hit in the chest with a baseball, for some reason his heart stopped and he fell to the ground. The coach (A local radio celeb) was there by him wne he fell and started cpr, kid is alive today but I wonder was it the ball hitting him, that dropped him? A kid threw the ball I doubt if it was over 65 mph.
 
Last deer I shot was knocked down, he was in mid air tho when the shotgun slug hit him so in all reality he fell as when the slug hit he couldnt run anymore and dropped right there.
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That's why there's so much disagreement. There's no one definition of "knock down". Your deer was so injured by the slug, that he immediately ceased to function and was dead in short order. The slug didn't knock him down, he just dropped (straight down) as a result of slug damage---not unlike the "knockdownpower" of a sudden severe heart attack.


Now, if the deer had been hit by a giant bean bag cannon and knocked over sideways, then that's what I'd call "knock down power".

Even if he go up and kept going.:D
 
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Well, then, is "stopping power" the same as "knockdown power" or not? I sort of think a lot of people believe that if knockdown power actually exists, then whoever or whatever is hit by a bullet will be knocked off their feet and flung backwards several feet (as seen on TV). I suppose that's entirely possible because it is more difficult to argue that something is NOT possible. However, for that to happen, the projectile probably would not be either passing through the body or expanding. But given that bodies are not solid, that shouldn't be likely. If the body were solid and hard, or protected by something like that, the effect on the body would be minimal. Soft armor is another story but that's straying from the point.

Yet it seems to happen. I recently read of one incident as reported by a man hunting sheep in Alaska with a .30-06. His bullet hit the sheep just above the heart at a range of about 200 yards, I believe it was, and the sheep flipped over. 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.

That was in November of 1968. Nine years earlier Gun Digest had an article about this very subject (which I haven't read recently), the title of which was: "Knock down nothing."

The controversy rages on.
 
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?
 
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?
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Considering just the force of the impact without the penetration/muscle tissue damage, reflexive nerve impulses, etc? As in stopping in the vest so as to simply absorb the full potential of the energy without the side effect of say... DYING? Go into a batter's cage and let the pitching machine smack you in the chest with a 70 mph throw. It'll bruise, throb, and really get your attention. But it's not going to knock you off your feet any faster than a bullet will all by itself.
 
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