Taylor KO Factor

Taylor KO Factor is a formulaic mathematical approach for evaluating the stopping power of hunting cartridges. The term "KO" is an acronym for "Knock Out." The Taylor KO Factor (TKOF) is a derived figure that allows hunters to compare bullets with respect to stopping power. The TKOF was developed by John "Pondoro" Taylor, a famous mid-20th century hunter and poacher of African big game. The factor is computed using Equation 1.

(Equation 1)

Where

• is the bullet mass in grains (1 pound = 7000 grains)
• is the bullet velocity in feet per second
• is the bullet diameter in inches

If the international standard units of grams, millimeters, and meters per second are substituted, the divisor can be changed from 7000 to 3500 to give approximately the same resulting TKOF.

Taylor first described this measure of stopping power in his classic work "African Rifles and Cartridges" (Reference 1). In this work, Taylor did not actually state Equation 1. In fact, he stated in Reference 1 that "I do not think there is any necessity to go into the methods I employed to arrive at the formula I used, suffice it to say that the final figures agree in an altogether remarkable way with the actual performance of the rifles under practical hunting conditions." However, it is obvious from the text and his presentation that he used Equation 1.

Taylor referred to number generated by Equation 1 as the "Knock Out Value" or "Strike Energy." Common practice today is to refer to this value as the "Taylor KO factor" or simply "Taylor KO."

In Equation 1, the denominator value of 7000 is a scaling factor. It can be viewed one of two ways:

• as converting the units of bullet mass from grains to pounds.
• giving the TKOF a convenient numerical value from 0 to ~150 for normal hunting cartridges.

The TKOF has no physical meaning or scientific basis and is strictly used as a figure of merit for comparing cartridges. Its main advantage is the ability to attempt to represent complex terminal ballistics as a number. This can be utilized to assign different wounding capabilities to projectiles in video games.