Taylor KO Factor


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4season
February 5, 2013, 11:35 AM
I have been reading around on this site and it seems many here don't like the Taylor KO Factor. I am curious why. I find it to be a much better number for comparing cartridges than energy. It takes the diameter of the bullet into account as well as the speed and weight. While it can't factor in bullet expansion or penetration it is a lot simpler than memorizing ballistic gel patterns.

I see many saying stuff like "It was developed for head shots on elephants" or something like that. Why does it mater how it was developed? The math seems to make since to me. For example if you compare a 45-70 to a .243:

45-70 at 100 yards
350g @ 1489 fps has 1723 ft/lbs of energy but has a KO of 34.1

.243 at 100 yards
100g @ 2788 fps has 1726 ft/lbs of energy but has a KO of 9.7

So does this not make since that a 45-70 would be 3 times as effective at 100 yards at bringing something down as a .243? The .243 has the same energy but even though the bullet is traveling twice as fast it is only 1/3 as heavy. If the .243 expands to twice its size it is then the same size as the non expanded 45-70. Sure seems to me that the 45-70 would be 3 times as powerful even though they have the same energy.

Now I know that bullet construction and shot placement are huge factors that can't be ignored in making a clean kill. But it sure seems that the Taylor KO comes closer to letting math approximate a clean kill.

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MCgunner
February 5, 2013, 11:49 AM
Attempts by gunwriters to assign math (in this case, 3rd grade level) to terminal ballistics is laughable. Just too many variables and factors are involved in terminal ballistics.

No, I do NOT believe the .45 70 is 3 times as effective as a .243, maybe 1.5 times or something, and it ain't got squat on a .270. If you want to learn a little about terminal ballistics and how complicated it really is, try this.

http://www.btgresearch.org/wb.htm

This guy is a PhD physicist working out of West Point, NY. He is a might more knowledgeable in both wound ballistics and mathematics than Taylor was. But, in Taylor's defense, he was working with large caliber dangerous game rifles stopping big beasts with solids. In this realm, his simplistic arithmetic, which is momentum biased, does make sense as momentum helps penetration through thick skulls.

jmr40
February 5, 2013, 12:19 PM
Bullets kill game by breaking body parts, not with math equations. They rely on 3 things to do that. Bullet placement, bullet penetration and bullet diameter, or expansion. Bullet diameter matters not one bit. You can start with a large caliber or a smaller caliber as long as it expands and gets the penetration needed. With todays modern bullets a 243 will give the same penetration and expand to the same diameter as a 45-70 and will break the same body parts.

Any of the attempts to predict a bullets performance based on math formulas always leaves out bullet construction. If you are comparing similar bullets, and similar velocity ranges they can be fairly accurate. If you compare all of the slow heavy chamberings such as 44 mag, 444, 45-70 etc. you can get a mathematical idea of which will perform best. Same when comparing modern high velocity, smaller caliber rounds such as 270, 30-06 etc. But when you compare a 45-70 to a 243 using any of these math formulas the resulting data is useless. Both kill, they just do it differently.

rcmodel
February 5, 2013, 12:44 PM
So does this not make since that a 45-70 would be 3 times as effective at 100 yards at bringing something down as a .243? No it doesn't.

It depends on the size of the target animal.

If you were to shoot a coyote with the 45-70, it would have a .45 cal hole through it.
There would be no time for bullet expansion.
It might run off some ways before bleeding out and dying.

Were you to shoot a coyote with the .243, it would have a 6mm hole going in, and a 3" hole coming out due to violent bullet expansion and hydrostatic shock, and it would be DRT.

Go to a truly big animal like a buffalo or whatever, and the roles would be reversed.

rc

4season
February 5, 2013, 12:48 PM
Bullets kill game by breaking body parts, not with math equations. They rely on 3 things to do that. Bullet placement, bullet penetration and bullet diameter, or expansion. Bullet diameter matters not one bit. .

Did you not just contradict yourself?

I agree that bullet placement is the key to a quick clean kill. But unless you can cleanly cut the spinal cord with every shot the math can help approximate the blood loss and nerve damage that will make a quicker kill.

Yes a 243 can expand and leave an exit wound as large as the entry wound of the 45-70 but the 45-70 can also expand and leave a much larger wound cavity thru the entire body. I am not saying that a 243 is underpowered, but many consider it to be the low end for deer. On the other hand the 45-70 is considered to be capable of taking any game in the world. In my example the energy is the same but the KO shows a huge difference. Does that not mean the the KO is a much better comparison than just energy? I am not saying that KO is the only thing that matters, nor am I saying that shot placement or bullet construction aren't huge factors that math can't compensate for. I am only suggesting that the Taylor KO is a better number than simple energy and that it may be a good starting point in comparing cartridges.

4season
February 5, 2013, 12:59 PM
No it doesn't.

It depends on the size of the target animal.

If you were to shoot a coyote with the 45-70, it would have a .45 cal hole through it.
There would be no time for bullet expansion.
It might run off some ways before bleeding out and dying.

Were you to shoot a coyote with the .243, it would have a 6mm hole going in, and a 3" hole coming out due to violent bullet expansion and hydrostatic shock, and it would be DRT.

Go to a truly big animal like a buffalo or whatever, and the roles would be reversed.

rc

Very good point on bullet construction. A small game bullet in a 243 would be much better than a dangerous game bullet in a 45-70 on a coyote. And I am certainly not aware of any small game bullets for a 45-70 so it would not be my go to gun for coyote. Maybe I should have said all other factors being the same, like if you were shooting FMJ in both that the 45-70 would be 3 times as effective.

H&Hhunter
February 5, 2013, 01:03 PM
With todays modern bullets a 243 will give the same penetration and expand to the same diameter as a 45-70 and will break the same body parts.

I agree but lets put that comment in context. On light boned thin skinned game you are correct. On heavy boned thick skinned game you are not correct. When it comes to heavy game we start to need some heavy momentum be able to achieve our required penetration. And even in the heavier calibers many times an expanding bullet will not give us the required straight line penetration needed to reach the vitals on heavy game and that is when we need to use solids and that is where diameter becomes a major player.

I've read Taylor's KO values and they valid, however they need to be adjusted for today's use of superior bullet technology. Remember that back in Taylor's day you had two choices on bullets. Either a full patch (solid) or an exposed lead (soft point) cup and core bullet.

All of this KO value stuff was meant to be applied to heavy game animals and elephant in particular. And when it comes to elephant and cape buffalo and such Taylor's KO values are still very valid with the added benefit of having super quality bullets we use now days. Taylor's KO values have never really been of much use if we are talking about shooting small deer or impala. Once you get to a certain point you've got "enough" gun to get the job done. A deer will die just as quickly from a well placed .375H&H as it will from a well placed .243. That is not usually the case with a cape buffalo. And it is in no circumstances valid in the case of an adrenaline soaked pissed off heavy DG animal such as a buffalo or an elephant or a lion. That is where some heavy duty KO value becomes extremely important. There is not a .243 round built that will penetrate the heavy neck muscles smash through the heart and exit after smashing the hind quarters on a charging buffalo. I'd dare say that there aren't many sub .40 cal 400 gr rounds producing over 4500 Ftlbs with a quality bullet that will.

In that situation a .375H&H becomes marginal a .416 Rem or Rigby becomes adequate and a .458 Win and up becomes useful. Having been there and done that I can categorically state that simply making a brain shot is much easier said than done. You need something with the horse power to give full length bone breaking penetration. And even that isn't a get out of trouble free card.

So plain and simple Taylor was not specifically talking about hunting deer in the USA when he came up with his KO values. He was attempting to give hunters coming to Africa a bit of knowledge that might keep them alive long enough to gain some experience.

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WHOOPS....


Just wanted to say that RC has it right. You guys posted all that stuff while I was writing the above. I took a coffee break mid paragraph so it took me a bit. So I don't mean to sound like I'm "over lording" what has already been said here. Sorry!!

MCgunner
February 5, 2013, 01:55 PM
I agree that bullet placement is the key to a quick clean kill. But unless you can cleanly cut the spinal cord with every shot the math can help approximate the blood loss and nerve damage that will make a quicker kill.

Doesn't account for the many bang flops I've had with simple lung shots. Courtney's ballistic pressure wave does. Read some of the papers. The math is intimidating, but the logic seems infallible.

Courtney was on this board some time ago and I conversed via PM with him. He, too, expressed that hunting with high powered rifles and the results he'd seen was his motivation for this research. He is working in most of this research with MUCH less energetic handgun rounds. With rifles, the ballistic pressure wave seems obvious. He claims that on the whole, it takes 500 plus ft lbs to see immediate effects of the pressure wave. I don't know, just know that rifles and thin skinned game in MY experience seem to bare him out.

It's all interesting theory, but I don't live my life around it. I do know that my .257 Roberts kills deer just as dead as my 7mm Rem Mag. THAT, you can take to the bank. AND, it shoots farther, is more effective at 300 yards, say, than my 50 cal CVA wolf or any .45-70 load just for the fact that I can make the hit with it. It's sighted in zero at 250 yards, so not much hold over at 300.

Patocazador
February 5, 2013, 03:06 PM
I don't trust anyone named Pondoro. ;)

StrawHat
February 5, 2013, 04:09 PM
Taylor's formula was for solid ammunition, as in non expanding. It was the only kind of bullet that made sense in his kind of hunting.

H&Hhunter
February 5, 2013, 08:11 PM
Taylor was very fond of exposed lead (soft point) bullets for buffalo hunting. he specifically recommends them to be used for the first shot and solids afterwards. he writes about it in several of his books.

And nothing has changed in that regard for elephant you should be using only solids but a quality controlled expansion bullet is my preference for buff.

Lloyd Smale
February 7, 2013, 01:22 PM
im another thats not a big fan off measuring a rounds effectiveness by any math equation. I like to rely on my actual field experience but if i had to choose i feel the taylor system is hands down more of an accurate measure of the effectiveness of a given round then energy figures.

saturno_v
February 7, 2013, 05:43 PM
I've read Taylor's KO values and they valid, however they need to be adjusted for today's use of superior bullet technology. Remember that back in Taylor's day you had two choices on bullets. Either a full patch (solid) or an exposed lead (soft point) cup and core bullet.

All of this KO value stuff was meant to be applied to heavy game animals and elephant in particular. And when it comes to elephant and cape buffalo and such Taylor's KO values are still very valid with the added benefit of having super quality bullets we use now days. Taylor's KO values have never really been of much use if we are talking about shooting small deer or impala. Once you get to a certain point you've got "enough" gun to get the job done. A deer will die just as quickly from a well placed .375H&H as it will from a well placed .243. That is not usually the case with a cape buffalo. And it is in no circumstances valid in the case of an adrenaline soaked pissed off heavy DG animal such as a buffalo or an elephant or a lion. That is where some heavy duty KO value becomes extremely important. There is not a .243 round built that will penetrate the heavy neck muscles smash through the heart and exit after smashing the hind quarters on a charging buffalo. I'd dare say that there aren't many sub .40 cal 400 gr rounds producing over 4500 Ftlbs with a quality bullet that will.

In that situation a .375H&H becomes marginal a .416 Rem or Rigby becomes adequate and a .458 Win and up becomes useful. Having been there and done that I can categorically state that simply making a brain shot is much easier said than done. You need something with the horse power to give full length bone breaking penetration. And even that isn't a get out of trouble free card.

So plain and simple Taylor was not specifically talking about hunting deer in the USA when he came up with his KO values. He was attempting to give hunters coming to Africa a bit of knowledge that might keep them alive long enough to gain some experience.


H&H

I largely agree...however what you call "momentum" I call it energy and sectional density (obviously we have to take in consideration the extremely important bullet construction)

A 243 simply does not have the horsepower nor the sectional density to do a good job on a buffalo like you said...and, accordingly, the bullet construction is not tailored for that kind of job.

On the other hand, the 160 gr. & up 6,5mm bullets out of the relatively mild mannered 6.5x55 Swede have slaughtered a lot of moose very reliably...decent horepower and tremendous sectional density...and I'm sure lot of folks consider the 6.5mmx55 too light for moose.

Going back to your buffalo example, within the 30 cal. family of cartridges, it would be a suicide facing one with a 30 Carbine, and almost a death wish with a 30-30.....however give me a 300 Weatherby or a 30-378 firing a 240 gr. Woodleigh Weldcore bullet and things start to look troublesome for the buffalo.....more energy and more sectional density, obviously assuming the bullet holding up.....

The most important parameters are bullet placement, energy, sectional density and bullet contruction...caliber is secondary.
In addition to that, some animals seem to respond very positively (meaning good for the hunter bad for the animal) to high velocity rounds.

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