"Knockdown Power"

[CraigC]

Wow quite a bit of misinformation, Roy Weatherby and gun writers did not invent modern ballistics. Neither did Taylor. Scientific engineers did. And the science of it has been determined for over a century although advances continue. Every major gun and ammunition company and major militaries have real certified scientists that spend thier career doing studies and know what they are doing. . Also Fackler is a coroner with no training in ballistics and much of what is he says is bias some lies and none of it actual scientific study. Really, study up on real experts with proven credentials.
The only accurate way the measure the potential of a projectile is kinetic energy . However the effectiveness of a particular cartridge is a combination of many factors. Ammunition should be selected by what it is designed for. But nothing is a substitute for proper bullet placement.

Nonsense. Kinetic energy as a gauge of a cartridge's effectiveness is easily debunked with but a few examples. It tells us nothing useful and it only a marketing tool for selling velocity.

 

[RecoilRob]

Nonsense. Kinetic energy as a gauge of a cartridge's effectiveness is easily debunked with but a few examples. It tells us nothing useful and it only a marketing tool for selling velocity.

Agreed! When given the choice....I'll go with an empirically derived formula over a 'scientific' one any day, because it was proven to work. Example: 45-70 slug of 500 grains delivered at extended range hits the bison @ 850 fps. This equals 800 ft/lbs and has proven hundreds of times to do the job. Fire a steel BB at 8500 fps and you deliver the exact same kinetic energy...but it's hard to imagine that they would perform equally on Mr Bison. The Taylor 'Knockout Formula' seems to work on large animals pretty reliably, enough so that you'll not go far wrong using it if in doubt about what to use for a particular game animal.

 

[mcb]

An 850 fps 500 gr 45-70 bullet has a TKO of 27. A 100 mph 2300 gr baseball has a TKO of 137.

They both have very similar momentum, 45/70 60 slug-ft/s vs baseball 48 slug-ft/sec

But their kinetic energies are very different, 45/70 802 ft-lbs and the baseball at only 109 ft-lbs.

Of those three KE is still the better predictor. KE and projectile construction can give you a very competent data set. 22 lr or fast pitch baseball to the chest? Both have roughly the same energy, the base ball has significantly higher TKO and momentum. KE and bullet specs* are what you want.

*there are lots of ugly details hidden in here with how reliable a bullet is.

 

[CraigC]

Energy is useless no matter how you look at it.

TKO was never meant to compare baseballs to bullets. It was also never meant to compare small bores to big bores. It is only viable for comparing big bores to each other. For that purpose, it is a useful tool.

Bullets aren't rated to expand at a certain energy level. They're rated for impact velocity. So again, energy tells us nothing useful.

 

[M118LR]

Perhaps it's time to find out what we all agree upon to better define what we consider "Knockdown Power" to mean?

Vel & B.C. are used to calculate trajectory.
Kinetic Energy is determined using Velocity & Projectile weight.

Stopping power (Knockdown power) : https://en.wikipedia.org/wiki/Stopping_power
The goal of determining "Knockdown" or "Stopping" power is to effect a one shot stop regularly upon the game being hunted.
TKO is a statistically based formula using proven field results to determine probable repeatable field results.

"Knockdown-Stopping" power is of primary concern at exceptionally short range. (usually less distance then the screens are set up at for a chronograph. )

 

[JohnKSa]

Knockdown Power, ICSA, Taylor KO Factor, and the plethora of other empirically derived numbers all have same short coming. If they work at all they only work for a very small range of values/conditions since they are not based on hard physics principals.

Correct. As you say, assuming they work at all.

Energy is useless no matter how you look at it.

Energy is certainly a useful quantity. Since it is a fundamental physical property of moving objects, it has real-world meaning and therefore value for those who understand what it means. The idea that it is simply a marketing tool is not only incorrect, it is a ludicrous claim.

https://en.wikipedia.org/wiki/Kinetic_energy
http://hyperphysics.phy-astr.gsu.edu/hbase/ke.html
https://www.livescience.com/46278-kinetic-energy.html

As early as 1722, it was proven that the amount of deformation caused by a ball hitting soft clay is proportional to impact velocity of the ball squared.

It is true that it can (and has been) overemphasized and that leads to confusion and misunderstanding. It is also true that many people don't understand it and what it means. However, underemphasizing it, or pretending it has no meaning or value will also lead to confusion.

I will agree that it is not possible to compare caliber performance across the board using nothing but energy values. In fact, I'll go a step farther and state that it is not possible, and I don't believe it ever will be possible to wrap caliber performance, across the board, into a single number that tells the whole story. It's more complicated than that.

Bullets aren't rated to expand at a certain energy level. They're rated for impact velocity.

Given that energy is dependent only on velocity and bullet mass, and given that bullet mass doesn't change from the time it is manufactured until the time it is shot, the bullet's rating can be stated either in terms of energy or velocity. It's just that stating it in terms of energy would require the consumer to perform a reverse calculation to determine the impact velocity. In other words, even though it is impact energy that is the primary factor in bullet expansion (bullet construction aside, and assuming a homogenous target medium), quoting the rating in velocity makes it much simpler for the consumer.

It is only viable for comparing big bores to each other.

To the extent that the TKO has any value, and without implying/agreeing that it does, I would agree that any value it does have is exclusively for comparing elephant guns.

That said, I think Taylor himself would disagree with your claim that it was "never meant to compare small bores to big bores".

His table of "Practical Striking-Energy" values goes down to calibers having bullet diameters as small as .240 and he comments that he included the "value of certain small bores to show that they cannot be considered safe weapons to take against dangerous game at close quarters in thick cover". Clearly he believed that his "Practical Striking-Energy" values provided a way to determine the relative performance of small bores to big bores.

 

[CraigC]

Energy is certainly a useful quantity. Since it is a fundamental physical property of moving objects, it has real-world meaning and therefore value for those who understand what it means. The idea that it is simply a marketing tool is not only incorrect, it is a ludicrous claim.

It is purely a marketing tool for selling velocity. Until we are able to determine just how the energy is used and to what effect, then it is of no use whatsoever. As is any discussion of energy, energy transfer or energy "wasted" on an exit. All based on a faulty premise.

My comments are always misconstrued in the same way and the response is always some condescending nonsense about "simple physics", to imply that I'm ignorant of physics, because apparently people read what they want to. I never said that energy was unimportant. I said it was a meaningless number that tell us nothing useful. Which is to say that energy itself is useful but the quantity generated is not. Which is not to say that it is not at work or doesn't exist. It's all too easy to provide just a handful of examples to show that energy is of no use. Been there, done that a hundred times.

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.

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

"Energy. Surely the most misleading thing in the world - where rifles are concerned. Gunsmiths invariably quote it because, particularly since the advent of the Magnum, it is decided flattering to their weapons. Personally, however, I take little notice of these figures. They're quite useless if you are trying to compare any two rifles from the point of view of the actual punch inflicted by the bullet. Muzzle energy is far too dependent upon velocity and tends to ignore bullet weight; but it's the weight of bullets that matters when it's a case of knocking down some beat at close quarters."

Simple examples show that using TKO to compare small bores to big bores is futile. Same for expanding bullets because an important factor in the equation changes as a bullet expands. However it does not only apply to "elephant guns" but to any big bore that depends on mass for effectiveness with non-expanding bullets. Which includes handgun cartridges, whether you would shoot an elephant with one or not is irrelevant.

 

[George P]

Back in the 'Old Days' the Taylor Knockout Formula was invented to help predict effectiveness on Big Game. http://www.n4lcd.com/calc/ It IS effective...but is mostly momentum based with equal parts of weight and velocity playing their parts. But then came Roy Weatherby who believed that smaller and much higher velocity bullets could equal or surpass the old thumpers, and in some cases he was right. The hydrostatic shock that the higher velocity projectiles impart on the CNS can put large animals down as if they were struck by lightning....and belie their Taylor KO predictions.

But....and there's always a 'But'...huh? When penetration on large game is needed, I'd go with the Taylor formula of heavier and better SD to ensure adequate performance where the lighter bullet might fail. With careful shot placement the smaller calibers can absolutely work just fine....but the stress on the projectile is magnified and many will fail. The very latest solid copper bullets seem to violate the conventional wisdom and can hold together while penetrating deeply so perhaps the playing field has been altered a bit. As always...the definitive answer remains....'It Depends'.

And then you have the old buffalo hunters who used a very big, heavy, slow-moving projectile to take down the largest big game animal we have - and at distance - because it penetrated all to a great depth..........

As always...the definitive answer remains....'It Depends'

Yep!

 

[d2wing]

Energy is useless no matter how you look at it.

TKO was never meant to compare baseballs to bullets. It was also never meant to compare small bores to big bores. It is only viable for comparing big bores to each other. For that purpose, it is a useful tool.

Bullets aren't rated to expand at a certain energy level. They're rated for impact velocity. So again, energy tells us nothing useful.

LOL, energy is useless??? Without energy the would be no motion at all. Do you have any education at all?

 

[d2wing]

Ballistic is a complex but known science. That is why ballistic engineers are able to design specific bullets for specific purpose. They know what to expect in general what will happen when a bullet enters flesh. Only a simpleton would say it depends only on mass or velocity. It depends on bullet shape and construction to be sure the bullet performs for it's purpose. It is the application of energy. All factors are important in applying energy to flesh. Energy is a measurement of how much force a projectile has. That part is easy. We all know that it takes a known range of mass and caliber plus appropriate construction to deliver that energy to the intended target. To say Energy is not a useful measurement of potential is not true at all. If you chose to prefer other methods that is your choice. But don't expect people to think you are credible. Especially when you mention Fackler. A well know quack.and liar. I do agree that heavy slower bullets have their place especially on large animals because of how bullets act in flesh with is largely fluid. A high mass bullet that does not deform will penetrate further, the higher the velocity the more resistance is generated so you have to pick what velocity to use. Velocity isn't always the right answer for penetration. Taylors observation may be useful on the specific subject of high mass bullets on very large animals. But it is not scientific in terms and measurement so it doesn't apply across the board.

 

[readyeddy]

That is the problem, many will focus on only mass or velocity, and usually it is velocity. So where energy is used as a predictor of effectiveness, it is susceptible to being manipulated by excessive velocity.

 

[d2wing]

The term knock down power is a poor choice of words really. It implies that a bullet's energy is used to actually force the target to move or fall down. No animal is a solid object. The bullet doesn't push on the entire body and rarely would move a whole body at all. I suppose we understand that it means to stop a critter which can be different from killing it. The key is bullet placement more than anything. The world record Alaska Brown bear was shot by an women with a single shot .22 LR. Draw your own conclusions.

 

[readyeddy]

Agreed. We should all understand knockdown to mean stopping a critter which can be different from killing it.

 

[d2wing]

That is the problem, many will focus on only mass or velocity, and usually it is velocity. So where energy is used as a predictor of effectiveness, it is susceptible to being manipulated by excessive velocity.

By whom? Although one poster thinks that a manufacturer did just that. And invented ballistic science all by himself too, lol.

 

[readyeddy]

Not necessarily by any poster in this thread. Craig just made an observation about the use of energy as a number which is easily manipulated with more velocity. In other words, if energy is used as a number (by itself), then the weight and velocity have already been multiplied against each other and we don't get to consider bullet weight for a particular application.

Edit: I personally know people who value velocity more than bullet weight, and they do not post on THR as far as I know.

 

[M118LR]

Do any of US, (screen names deleted to protect the guilty) actually want to be armed with a 22 LR when facing a charging Alaskan Brown Bear? Can anyone predict the odds of success? (statistical field data) Of actually stopping an Alaskan Brown Bear with a single shot from a .22 LR? Why do most Alaskan Guides opt for 45-70 manual actions as a minimum to backup high paying clientele?

When it comes to stopping a charging "LARGE Dangerous Game Animal" at distances measured at the most in feet if not inches, penetration is the most significant factor of any formula! Large diameters and deep penetration seem to usurp high velocity and highly fragment-able small projectiles.

A knowledge of FRONTAL ANATOMY of the game animal in question is highly desirable, especially when you only have the rifle you came to the dance with. I'm going to the dance with a Large Bore Higher Sectional Density projectile at near muzzle velocities, BC at incredible distance isn't going to factor into the equation, the Larger the Bore HSD Solid Projectile that has proven field performance on hundreds if not thousands of actual field solutions is going to be my choice to carry afield. Yes, velocity will be formulated as it is a factor of felt Shooter Recoil, but as long as your shoulder can handle the rounds recoil while keeping the projectile "True" in paces, anything less might be a miscalculation. (add that into your mathematical paradigm)

Why is it that folks that earn a living stopping Large Dangerous Game Animals from eating their clientele base thier rifle/cartridge combos on empirical formulas?

 

[RetiredUSNChief]

Late comer here, but I can sum up "knockdown power" in one word:

Mythical.

Just like "stopping power".

 

[M118LR]

Late comer here, but I can sum up "knockdown power" in one word:

Mythical.

Just like "stopping power".

Never had a one shot stop? (Mythical)
Want to compare gnaw marks/scars?
LOL.

 

[CraigC]

LOL, energy is useless??? Without energy the would be no motion at all. Do you have any education at all?

Hey, try reading the friggin' thread and keep the personal nonsense to yourself. Perfect example of what I was talking about, even AFTER I pointed it out.

My comments are always misconstrued in the same way and the response is always some condescending nonsense about "simple physics", to imply that I'm ignorant of physics, because apparently people read what they want to. I never said that energy was unimportant. I said it was a meaningless number that tell us nothing useful. Which is to say that energy itself is useful but the quantity generated is not. Which is not to say that it is not at work or doesn't exist. It's all too easy to provide just a handful of examples to show that energy is of no use. Been there, done that a hundred times.

 

[M118LR]

Hey, try reading the friggin' thread and keep the personal nonsense to yourself. Perfect example of what I was talking about, even AFTER I pointed it out.

Don't kill the messenger.
Take issue with the message, don't attack the courier, don't succumb to personal attacks just highlight your personal opinions on the topic at hand. just my translation.

 

[CraigC]

I don't take kindly to personal comments and it ain't the first time for that particular individual. I just posted a comment about that very subject but some folks don't bother reading a thread before responding to it.

 

[M118LR]

I don't take kindly to personal comments and it ain't the first time for that particular individual. I just posted a comment about that very subject but some folks don't bother reading a thread before responding to it.

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.

 

[cjwils]

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.

 

[Propforce]

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.

 

[Panzerschwein]

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.

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