Help with an Argument on "knock down" power

[Aguila Blanca]

Originally Posted by Tennessee Gentleman

So any physics folks here? This is his reply as to the application of Newton's Law.

"Enough with the Newton’s Law crap! When used as an argument it sounds good, and apparently is very popular, but it does NOT work as you suggest. As I said before, that is simply throwing out a fine sounding physics term, but not doing the calculation! Except when the weight of the firearm is equal to the weight of the projectile, the weapon design includes no springs, slides, ejection mechanism or any other force mitigating features, then it does apply as you suggest.

Most of his variables can be eliminated by using a Colt SAA revolver instead of a 1911 -- and that has a more powerful cartridge, so that mitigates the recoil absorption of the firearm itself.

That said, the essence of science is to prove the theory through experimentation. Several people have already suggested that he put his assertion to the test -- buy a bag of mason's sand from Lowe's or Home Depot for five bucks, balance it in a vertical orientation, then shoot it from 15 or 25 feet away and see how far it moves.

Several years ago I was at competition night at the range where I shoot. That night the competition included a plate rack. I was shooting a 1911 in .45 Auto, using standard power FMJ ammo (most likely Winchester white box). When my turn came, I started blasting away -- and nothing happened. The RSO confirmed that every shot hit a plate, but the plates didn't fall. I don't know how much the plates weighed -- they were 1-inch thick, so if they were 8 inches in diameter they would have weighed just about 15 pounds. They had to adjust the setting on the rack so the plates would almost fall over by themselves.

Not long after, the range bought a new set of plates, made of hardened alloy to withstand bullet impact, that were only 1/2-inch thick. Those work much better.

My point being that if a standard power .45 bullet won't knock over a 15-pound steel plate, it certainly won't knock over a 200-pound human being.

[redhawk45]

Have you ever gone hunting? Shoot a deer with a 30-06 and it will likely crouch and run then fall over nearly dead. Shot several that fell right there but were kill shots to the neck and the deer was not knocked down.

[74A95]

https://en.wikipedia.org/wiki/Stopping_power
https://gundigest.com/how-to/truth-b...nockdown-power
https://www.buckmasters.com/Magazine...own-Power-Myth
https://www.outdoorlife.com/articles...m-flatten-game
https://www.range365.com/myth-knockdown-power

[Glenn E. Meyer]

I love 1911 mythology. In separate conversations, two big guys (over 6' 2") told me that they once fired a 1911 and it 'damned near tore their arms off'.

Little ol' 5 6" me said, well, look at my hand, I fired about 100 230 gr. rounds this weekend, and I'm still seeing my hand. Oops.

The videos are convincing as is the math! Thanks for the analyses.

[jackstrawIII]

You're right. And your friend is dead wrong about the force exerted by the bullet on the shooter. As soon as the "pressure vessel" is broken (the bullet leaves the barrel), the bullet no longer exerts any force on the shooter.

Interesting story: back in the old days when bullet tech was in it's infancy, the govt chose bullets/loads/firearms by shooting hanging corpses. Whichever load swung the corpses farthest, that was their choice. Was a flawed way of thinking then, and is a flawed way of thinking now haha.

[TXAZ]

Originally Posted by Cheapshooter

The youtube of the episode has been blocked by the network, but Mythbusters did this very experiment. They couldn't even knock down a man sized dummy with a 50 BMG!

The physics is straight forward and simple, but you have to identify and solve for the not-so-obvious issue:
While Mythbusters may not have been able to knock over a man sized dummy with a .50 BMG, the issue is the energy absorbed by the target. If half the 12K ft lbs of energy had been absorbed by the 200 pound dummy, 6000 ft-lbs/200 lbs = moving the dummy 30 feet.
Clearly the dummy in the Mythbusters experiment didn't absorb much of the energy.
Take an extreme example: What happens when a 660 grain / 12,000 ft lb .50 BMG round hits a 20 gram / 300 grain target. If most of the energy was absorbed by the paper, the paper should travel a very long distance (miles without wind resistance). But it doesn't because it takes very little energy (a few ft lbs) to poke a hole in a piece of paper.

So the trick to "knockdown power" is the target absorbing the kinetic energy. In an ideal world, a "bullet trap absorbs all the kinetic energy of a bullet.

If a bullet passes through a body, much of the 'knockdown power' is lost.

[dano1200r]

Video https://cloud.tapatalk.com/s/5a7db7984992e/lifted.mp4

[44 AMP]

Without going into every calculation [I’ve showed enough work here—BTW, I did not just look this up somewhere, I calculated it then used online tools to check my work], for a .45 that weighs 2.5 pounds (an empty standard 1911 is 2.4 so I rounded), the backward force (recoil) is 8 ft-lbs. (Which is less that dropping a 1 lb weight from 3.5 m)

Not going to check your math, nor argue with your application of formulae, but consider this, the calculated muzzle energy of a .45 round is around 360ish ft/lbs. Equivalent to dropping a 360lb weight ONE foot.

Science is only science if it is applied. “Science” doesn’t tell us anything. Newton does not support the argument, when actually applied."

This is the key, call it science or math, it must be applied correctly to the situation, and even then can be correctly applied and still not explain observed results.]

Math can "prove" or disprove almost anything, depending on how it is applied. Math (according to the old story) tells us that a bumblebee cannot fly. Yet, the bee, not knowing math, flies just fine.

A saw a physics problem once, a swimmer at a pool, starts on the edge, dives in, swims to the other end, then back, and gets out right where he started. Math "proves" he went nowhere. (the exercise was to use the math and show he went nowhere) And, under math rules, it did prove he went nowhere.

Trouble is, in the real world, he did go somewhere. We saw him swim the length of the pool, and then back. distance was traveled. We observed it. But, math, applied in a certain way, says he went nowhere, since he ended up right where he started.

This is the thing about "knockdown power". It is real, it is an observed effect. You cannot deny the effect exists, people have seen it, many, many times.

However, there is, to date, no theory or formula that explains it, and none that reliably predicts it. Many have theories and ratings that appear to be correct in some situations, but do not accurately fit observed results in ALL situations. Some use energy as their main factor, some use momentum, some include bullet shape, NONE have proven accurate across the entire range of situations.

I believe none can. I believe the observed "knock down" effect is something
that happens only when shooting living animals (including people). Shooting something else does not, and cannot replicate the effect.

I believe the effect is created not by the energy or momentum, or shape of the bullet in any quantifiable way. I think it is the reaction of the body's nervous system "short circuiting" in some way, as a result of the bullet strike. it is the muscles of the animal, driven by these nerve impulses that "knock" it off its feet, when that does happen.

Because it doesn't always happen. And when it does happen, it happens in random direction and strength. Every different bullet strike contains a host of different factors, which are simply not quantifiable and so cannot be accurately used in any equation. The biggest of these is simply that every individual animal or person shot is a different individual.

There is a bell curve of results, and while the majority will be in the middle of the curve and therefore show similar results, there are situations on each end of the curve where the results are vastly different.

One guy might be "blown off his feet" by a hit from "X" and another hit with the same thing, in the same place might just stand there, or even be "blown" forward, rather than backwards. I believe the difference is due to how the target's nervous system reacted to the shot, or didn't, not because of the calculated anything about the bullet itself.

In other words, one guy might get spun around from a hit in the hand with a .45acp (and probably did, somewhere, sometime, and so the legend is born) while the next guy, shot in the hand might just look at the hole in his hand, and think, "hmm, damn, I've been shot..."

My personal theory is in my signature line, and note that its not stated in absolutes, and is based on my lifetime of observed results.

[ThomasT]

He is a .45 ACP guy.

So, what am I missing?

The chance to just smile and let him believe what he wants to believe. Its an argument you most likely won't win. You have to choose your battles.

[Glenn E. Meyer]

With about 2% of the population, they have an exaggeration response to injury and basically faint when they see or feel a penetrative wound, see blood, or think they were injured, etc.

That might explain some of the folks who get a minor hit and keel over.

[zukiphile]

Originally Posted by TG

So any physics folks here?

I'm not a physicist, but I drive by a Holiday Inn each evening.

I went to school with a fellow who was a boxer in the Army. He was my size but in better shape and his hands were so fast I couldn't follow his fists with my eye. Had he punched me in the face or my solar plexus, he'd have certainly knocked me down, but not because his punch had the force to take a couple of hundred pounds and move it a few feet. And, of course, his own punch didn't knock him down either.

It seems reasonable that a handgun round with good power delivering a bullet to the right spot could put someone down just like a well delivered punch, but that isn't the same sort of knock down as one football player running into another so as to knock a player off his feet.

[mehavey]

Guys, what part of this actual demonstration (@1:00) is unclear ?
https://www.youtube.com/watch?v=BgZPusyLeMA

Sooner or later you have to quit playing with cocktail circuit theory, and just go out and do it.




and if you don't like that, then play the romp`em stomp`em 12 gauge slug (2,500ft-lb) doing 1,600 game. (@3:00 same video)


.

[Tennessee Gentleman]

Originally Posted by 44 AMP

but consider this, the calculated muzzle energy of a .45 round is around 360ish ft/lbs. Equivalent to dropping a 360lb weight ONE foot.

Actually according to thishttp://gunownersofcanada.ca/showthre...-EFFECTIVENESS

"Goddard amply proves the fallacy of "knock-down power" by calculating the heights (and resultant velocities) from which a one pound weight and a ten pound weight must be dropped to equal the momentum of 9mm and .45ACP projectiles at muzzle velocities, respectively. The results are revealing. In order to equal the impact of a 9mm bullet at its muzzle velocity, a one pound weight must be dropped from a height of 5.96 feet, achieving a velocity of 19.6 fps. To equal the impact of a .45ACP bullet, the one pound weight needs a velocity of 27.1 fps and must be dropped from a height of 11.4 feet. A ten pound weight equals the impact of a 9mm bullet when dropped from a height of 0.72 inches (velocity attained is 1.96 fps), and equals the impact of a .45 when dropped from 1.37 inches (achieving a velocity of 2.71 fps)"

Goddard, Stanley: "Some Issues for Consideration in Choosing Between 9mm and .45ACP Handguns", Battelle Labs, Ballistic Sciences, Ordnance Systems and Technology Section, Columbus, OH, presented to the FBI Academy, 2/16/88, pages 3-4.

[JohnKSa]

Clearly the dummy in the Mythbusters experiment didn't absorb much of the energy.

The dummy was rigged with an armor plate in the torso. The bullet did not pass through the dummy in the test--it was stopped in the torso.

The dummy was dislodged from its supports but it fell more or less straight down after that.

[tangolima]

First we need to properly definite "knock down". Without a definition, we just get hand wavings of different kinds.

Physics is study of energy transfer. A rifle bullet has kinetic energy of 1000 ft-lb. That energy can lift a 1000lb straight up by 1 foot. That is a lot of energy. The only question is how to transfer that energy to the object that we want to move.

Newton's 3rd law is surely valid. But it needs to be applied correctly, or it is just used to wave more hands. Say I stand a few feet from you. I have a sludge hammer is my hands. I swing that hammer and hit it square on your chest. You will be on the ground a few feet back, and I will be standing. Newton's 3rd doesn't work, does it?

-TL

Sent from my SM-G930T using Tapatalk

[K_Mac]

The exaggeration response is a very real phenomenon. I've known my father-in-law for over 40 years, and he has always responded in a very exaggerated way to any physical contact, loud noises, or input. Damnedest thing I have seen. I quite sure he would be knocked down by a .22 lr round fired into a vest.

[Tennessee Gentleman]

Originally Posted by tangolima

First we need to properly definite "knock down". Without a definition, we just get hand wavings of different kinds.

Here is what I would use. The force required to knock an average sized person standing normally while conscious and sober off their feet to the ground by only the force applied (not physio or psychological reasons) of the bullet striking them. Is that ok?

Hand waving? Do I know you?

[Tennessee Gentleman]

Originally Posted by JohnKSa

The dummy was rigged with an armor plate in the torso. The bullet did not pass through the dummy in the test--it was stopped in the torso.

So the dummy received the full force and it was not dissipated by penetration?

[44 AMP]

I quite sure he would be knocked down by a .22 lr round fired into a vest

I'm not so sure I wouldn't be knocked down by a .22LR round fired into a vest!

I've never been shot by a .22lr fired into a vest, so I don't know, for SURE, but I think it might be likely, if I didn't expect it. (and since I'm a LONG way from 25 and the peak of health and balance, its quite possible!)

One of the funnier things I've ever seen was a news clip that was in a "bloopers" show I saw ages ago.

An reporter, standing in front of the camera, holding his mic and wearing a bulletproof vest over his suit jacket. The reporter tells us about the new vests the local cops are getting, and how they "really work" And then he says, "and to prove it, I'm going to let them shoot me!!!"

At this point, a hand holding a small shiny revolver (nickle or stainless) appears out of the right side of the frame, distance a couple of feet away.
There is a POP sound (all gunshots become "pops" on video tape) and no apparent recoil of the revolver.

The reporter staggers back several steps, stumbles and falls, dropping the mic. He slowly gets to his hands and knees, picks up the mic and stands up, and we hear a slightly muffled "Oh F(bleep), that hurt!!"



I do not think the reporter had been adequately briefed on what was going to happen. He wasn't incapacitated, but he was KNOCKED DOWN by the little round hitting the vest.

The bullet didn't physically knock him over, but he was knocked down by his own reaction to being shot.

Plug that into various formulas and see how it computes!

I've talked with people who have been shot. Some describe it as a "hammer blow", others said "a fierce burning sensation", one guy (a cop) said he didn't even know he had been shot, until after the gunfight was over....

Everyone is different, and some people are very different. I don't think there is any math that can take that into account, accurately.

Formulas and statistics may be useful for comparing different rounds to each other, but their accuracy in predicting real world results is 50/50, each and every shot. The real world either behaves in line the formula, or it doesn't.
Flip a coin, its just as accurate a predictor...

[tangolima]

Originally Posted by Tennessee Gentleman

Here is what I would use. The force required to knock an average sized person standing normally while conscious and sober off their feet to the ground by only the force applied (not physio or psychological reasons) of the bullet striking them. Is that ok?

Hand waving? Do I know you?

Stick one hand out, palm facing down. Rotate the forearm back and forth in a oscillating manner, so that the sticking out hand moves in mid air like ocean wave. While doing that, you are making statements filled with "something like that", "like", "stuff" and lol. That's hand waving, not the kind you do when seeing your neighbor.

Your definition is good. I would add the person's feet are tied together side-by-side, so that he can't be in a "horse stance". I think energy of 1000 ft-lb should suffice. I haven't tried it myself and I am not going to suggest any experiments. America is no longer land of the free, but land of the blamed.

-TL

Sent from my SM-G930T using Tapatalk

[UncleEd]

Hey, no, I know more than you do!

Oh yeah, well I've got three doctorates
in physics!

Your doctorates don't amount to a hill
of beans compared to my experience!

Heck, none of you know as much as I do!

Wait, I have the answer, it's, it's, it's
time for dinner. Afterward, let's try
for a three-page thread or maybe four.

[briandg]

your friend is wrong. He doesn't understand physics or guns, and you are wasting your time.

If he can't watch a guy shooting steel plates that just bounce a little and understand the facts, he's never going to get it and it's not worth the effort to try and break through that thick head.

I watched a guy shoot a 100 yard partridge target with a .44 magnum, I guess the target weighed five or more pounds, the thing stopped about ten to fifteen feet from impact after falling and rolling.

Now if a .44 magnum could barely knock down a steel block, doesn't it also follow that a .44 magnum would have a really hard time "knocking down" a nice water filled jelly bag that weighs about forty times as much? If a .44 magnum can't knock down that bag of gunk and bones, could a .45 acp do it?

Measuring "knock down power" is the simplest thing that you could ever test. Start knocking things over. If you do some very extensive testing, you will probably find that anything much heavier than a log will "fall" down, and knock down is the absolutely worst way to describe that.

[JohnKSa]

So the dummy received the full force and it was not dissipated by penetration?

The .50 BMG bullet did not penetrate through and through, but it did penetrate into the dummy considerably, even going through the armor plate. After passing through the armor plate, it was stopped in the steel "spine" of the dummy and did not exit.

[Plunderer]

Imagine a bucket of water. If you smack the water with an open hand, it will make a big splash and displace a lot of water. This is because your hand is striking the water with considerable force, but it is spread over a wide area, so it doesn't penetrate very deep. If I plunge my fist into that same bucket of water, I will likely hit the bottom with ease. This is because, even though I am moving my arm at the same speed and with the same force, my fist has less surface area than my splayed hand. The force is more "concentrated".

It's the same way with bullets. Most bullets simply aren't wide enough to reliably knock someone off their feet from impact alone.

[Bill DeShivs]

Plunderer- bullets simply don't have enough energy to knock people down.