"Knockdown Power"

Propforce · Mar 6, 2018

cjwils said:
I have shot approximately 10 deer using a .243 Win with expanding bullets of 85 or 90 grains and muzzle velocity above 3000 fps. Most were shot at less than 100 yards, so velocity was still very high. With even a semi-good hit, all of the deer collapsed like a wet noodle and did not get up again. At least half of these deer fell toward me, so "knockdown" is not an issue. On field dressing these deer, I have found tremendous internal damage. Sometimes, a volume as big as an orange inside the body cavity is turned to hamburger mush. One time I found that the heart was mostly missing -- turned into unidentifiable hamburger mush. That kind of damage causes immediate collapse. No big, slow bullet can do that, no matter how high a big slow bullet might score on some scale of knockdown or stopping power.

Others who used big slow bullets (.35 Whelen/ Remington) have observed the same on deer, dropped dead right there. How do you explain that?

Propforce · Mar 6, 2018

Cooldill said:
Wrong. All you have to do is use the square root. It makes the models smaller and therefore easier to quantify.

Haha... I trust you are kidding. :rofl:

CraigC · Mar 6, 2018

M118LR said:
Didn't mean to rub your rhubarb CraigC, but perhaps cooler heads shall prevail? Sounds like it's time for me to bail on this particular topic. TTFN.

You didn't.

JohnKSa · Mar 7, 2018

It is purely a marketing tool for selling velocity.

Which ammunition company was Gottfried Leibniz working for when he discovered energy in the late 1600s? Which bullet was Emilie du Chatelet marketing when she did her experiments confirming the validity of Liebniz's energy theory in the early 1700s?

I never said that energy was unimportant. I said it was a meaningless number that tell us nothing useful.

It is important, meaningful and useful. It doesn't tell the whole story, by any means (no single number can), but it does provide very useful insight into certain aspects of terminal ballistics.

It's all too easy to provide just a handful of examples to show that energy is of no use.

It is all too easy to use examples to prove that one does not understand energy and how it applies to terminal ballistics (or perhaps simply rejects it without even trying to understand), however it is impossible to show that it is of no use in that field because its utility was already firmly established via repeatable experiments long before any of us were born.

Yes, let's talk about what John Taylor actually said:

I quoted what he actually said and it disagreed with your assertion of how he intended his "Practical Striking-Energy" figures to be interpreted. Why aren't we talking about that instead? Getting one quote right doesn't mean that your previous misquote/mischaracterization suddenly becomes accurate.

Simple examples show that using TKO to compare small bores to big bores is futile.

I agree with that statement 100%. However, I was responding to a claim that TKO was "never meant to compare small bores to big bores". Taylor explicitly stated that he included some small bores in his table just for that exclusive purpose.

Bullets are rated for impact velocity. Converting this to energy is not only never done but it is also not useful. What would be the point? There is none, it's irrelevant. There would be absolutely no point in rating bullets for energy levels.

Bullet ratings are quoted in terms of impact velocity for the convenience of the consumer, but the operative factor in bullet expansion/deformation is impact energy since that is the quantity that is "used up" in the process of deforming the projectile. In other words, the actual rating and design is based on impact energy but provided in terms of impact velocity for simplicity/convenience.

In my simple mind, too many are obsessed on the energy/ momentum of incoming ballistic but failed to understand how much of that energy/ momentum absorbed in the receiving body that constitutes “knock down power”.

Also, the “body” is not made up of homogenous constituents. It’s a complex mechanism with “mental determination “ extremely difficult to quantify. All these makes a simple formula, even complex mathematical models, impossible to quantify.

There's a lot of truth to this. It is a mistake to overemphasize energy or to pretend that it means more than it does--and unfortunately that is all too common. But dismissing it is just as big of a mistake. It just needs to be taken for what it is, nothing more or less. I agree 100% that trying to boil terminal ballistics in living tissue/knockdown power/stopping power down to a simple formula is not a productive activity.

RecoilRob · Mar 7, 2018

One thing that is muddying the discussion is that people are confusing hunting with STOPPING. Yes....a 243 can kill deer like being struck by lighting, and no doubt could also kill very large beasts with careful shot placement and bullet selection. But...sniping while waiting for the unsuspecting victim to turn exactly the right way and present the proper shot is WAY, WAY different than having something large and toothy coming to eat you. What will work most excellently with that careful shot could fail miserably (and fatally) when pressed into close range defensive type action.

Mr Brown Bear is wounded and deep in the thick stuff....and you have to go in and get him. Your .243 would do the job just fine when he's unsuspecting and you carefully place the bullet between his ribs and destroy his heart. Now he's less than 30 yds away and will only present you with a frontal shot while coming at you like a freight train with teeth. Will you still have confidence in the .243...or would you like to borrow your friends 416 Rigby? I think most of us would go for the Rigby...right?

I think we're all pretty much on the same page here and only bickering about the semantics.....but can we agree that one school of thought can work for both scenarios (that being the big-N-heavy) while the other more energy dependent school (small projectile at high velocity) can take game very well...within the limitations they have. If you had to carry only ONE rifle...it most likely would be the bigger one when the game can fight back.

mcb · Mar 7, 2018

JohnKSa said:
Which ammunition company was Gottfried Leibniz working for when he discovered energy in the late 1600s? Which bullet was Emilie du Chatelet marketing when she did her experiments confirming the validity of Liebniz's energy theory in the early 1700s?It is important, meaningful and useful. It doesn't tell the whole story, by any means (no single number can), but it does provide very useful insight into certain aspects of terminal ballistics.

{snip}

.

The amusing part is that Willem 's Gravesande who provided some of the early experimental evidence supporting Leibniz and Bernoulli conclusions, that kinetic energy was proportional to Mass times Velocity Squared (E∝mv^2) did so in large part using a simplified terminal ballistic experiment. By dropping weights from varying heights into blocks of clay the found that penetration was linearly proportional mass but proportional to the impact velocity squared.

Robert · Mar 7, 2018

Oh look, another thread about knockdown power has gone off the rails. Shocking...

"Knockdown Power"

Propforce

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Propforce

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CraigC

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JohnKSa

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RecoilRob

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mcb

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Robert

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