Taylor Knock Out (TKO) Scale

Discussion in 'The Ammo & Reloading Forum' started by mesinge2, Mar 3, 2010.

  1. mesinge2

    mesinge2 Member

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    I thought some people might like this data. I computed it based on the factory released velocity information with their corresponding barrel lengths during their tests.

    TKO Scale Compairsons.jpg

    Added at request of steve4102 Corbon Self-Defense 10mm Auto 165 Grain JHP's TKO is 11.59, impressive

    The formula used in the John "Pondoro" Taylor Knock Out (TKO) Scale for measuring power of calibers. Developed by an African hunter named John "Pondoro" Taylor. Basically, you multiply diameter of bullet in inches times muzzle velocity times bullet weight in grains divided by 7,000.


    P.S. the 25 suprised me
    Last edited: Mar 3, 2010
  2. petesusn

    petesusn New Member

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    Maybe I'm missing something here but I don't need a mathamatical formula to tell me that the 500 Mag is more powerful than the 454 which is more powerful than the 44 Mag ect, ect. Give me energy figures (with different loads for the same caliber) for 10, 15, 25 yards and I'll be better able to figure what's able to stop a man, a rabid dog, a rhino, or whatever the best. Now I'm not knocking your chart. For some it might be good info but for me it's telling the obvious.
  3. steve4102

    steve4102 Former Guest

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    What, no 10MM Auto??:)
  4. ofitg

    ofitg New Member

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    mesinge2, you can really open a can of worms with this thread. As far back as I can remember, people have debated various methods to calculate a load's efficacy.

    I hadn't heard about the Taylor KO scale until now.... so, how does the Taylor method handle the difference between, say, a 9mm 124gr JHP vs. a 9mm 124gr FMJ? Do you assume that the JHP has expanded to some specific diameter, and then plug that number into the formula?
  5. mesinge2

    mesinge2 Member

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    I don't think it factor's in bullet design at all. Which is unfortunate.


    As for the 10mm, I just forgot sorry. I added the 10mm to the OP
  6. jdon72

    jdon72 New Member

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    Hmmmm...don't know about this one. Most of it is common sense. The bigger the cal, the more knock down per-sey. The 357 short is not as powerful as the 9mm. I would say the reverse. But that is MOP.

    J
  7. ofitg

    ofitg New Member

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    The TKO method reminds me of the old Hatcher Relative Stopping Power formula :

    RSP = M * V * A* F

    M = bullet weight in pounds (ie, grain weight / 7000)

    V = velocity in ft/sec

    A = frontal area in square inches

    F = factor which varies with bullet shape. This factor ranged from 0.9 for jacketed round nose slugs, up to 1.25 for lead wadcutters.

    Hatcher's formula doesn't account for expanding bullets either.... it was the result from some U.S. Army tests conducted in 1904. Expanding handgun bullets were unheard of back then.
  8. mesinge2

    mesinge2 Member

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    I checked this, the reason is because the 9mm was tested in a 4 inch barrel and the 357 short was tested in a 2" barrel; hence the difference.
  9. steve4102

    steve4102 Former Guest

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    My calculations of the 10MM Auto are a bit different.

    180gr bullet X .400 dia. X 1287fps / 7000 = 13.24 TKO

    1287fps is per Hodgdon data, I run 9.2gr of Longshot to 1305 avg fps.
  10. Alpo

    Alpo Well-Known Member

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    If it was developed by an African PH, I would guess it has nothing to do with pistols, but was developed for dangerous game rifles. That would explain why bullet design isn't factored in. It doesn't matter. You use solids.
  11. ofitg

    ofitg New Member

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    If you like the "mathematical" approach for predicting handgun bullet effectiveness, you might enjoy the book Street Stoppers, written by Marshall & Sanow. They compiled "one shot stop" probabilities for more than a hundred different loads, based upon thousands of actual police shooting reports. The book also contains data from bullet tests in 10% ordnance gelatin, and promotes a mathematical formula developed by a guy named Fuller.

    If you're a REAL glutton for punishment, I might suggest the book Bullet Penetration, written by Duncan MacPherson. This book advances the views of the International Wound Ballistics Association.... very scholarly, but the math gets over my head in places.
    The IWBA thinks that the best predictor for bullet effectiveness is the permanent crush cavity created in 10% ordnance gelatin, providing that the bullet penetrates at least 12 inches..... and for mathematical purposes, any penetration over 15 inches is regarded to be "15 inches"..... they figure that the average bad guy is only 15 inches thick, so any penetration beyond that depth is irrelevant.

    The good news is, the gelatin tests in the Marshall-Sanow book include the data for permanent crush cavity (and penetration), so you can use those numbers for the IWBA approach if you want to.
  12. mesinge2

    mesinge2 Member

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    The 165 grain bullet in my calculations is the reason for the lower TKO value
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