The Taylor Knockout Factor: A way to rank the baddest calibers, or just B.S.?

Big-game hunter John “Pondoro” Taylor developed a formula he claimed codified the “knockout” power of rifle cartridges. Is it a reliable measure of a round’s efficacy, or an antiquated theory with dubious origins?

The study of ballistics has filled numerous textbooks through the ages and remains a contentious topic full of conflicting theories and mathematical equations that would drive Pythagoras to drink. It’s no wonder, then, that many hunters and firearm enthusiasts eagerly embrace simple, understandable arguments that support their opinions of which calibers are best.

One such formula can be attributed to Irish big-game hunter, sometimes-poacher, and author John “Pondoro” Taylor. In one of Taylor’s books, “African Rifles and Cartridges,” he introduces the eponymous Taylor Knockout Factor (TKOF), developed with the intent to codify and rank the practical ballistic prowess of large rifle calibers.

The title Knockout Factor may seem a bit hyperbolic at first blush, but Taylor chose this for a specific reason. He claimed a headshot on an elephant that missed the animal’s brain would still knock it unconscious for a brief time. Cartridges with a higher TKOF rating would, according to the author, keep the elephant unconscious longer, thus proving their knockout power. “They [TKOF figures] permit an immediate comparison being made between any two rifles from the point of view of the actual punch delivered by the bullet on heavy, massive-boned animals which are almost invariably shot at close quarters,” Taylor wrote.

The TKOF formula multiplies bullet weight in grains by bullet velocity in feet per second by bullet diameter in inches, then divides the result by 7,000—the number of grains in a pound. Without much scrutiny, this seems like a reasonable formula to quickly and simply identify the potency of a cartridge. For instance, the mighty .416 Rigby firing a 400-grain bullet at 2,400 FPS would score a 57.7, whereas a comparatively modest .30-30 Winchester firing a 150-grain bullet at 2,100 FPS would score a 13.

The problem

First, Taylor openly and repeatedly admits to having no background in mathematics or physics, and so makes no attempt to validate his formula by analytic means. “I have endeavored to deal with my subject and discuss the various rifles from the point of view of practical hunting, and so far as possible to avoid technicalities. I have done so because in the first place my knowledge of theoretical matters is insufficient, and in any case I have a notion that the practical aspect will interest a greater number of sportsmen.”

When addressing the origins of his formula, he once again downplays the importance of the mathematical aspect of ballistics in favor of empirical observation. “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.” You recall high school math class? Remember being asked to show your work to reveal how you arrived at the answer? Turns out there was a reason for that. It undermines one’s credibility when, upon being asked how you arrived at an answer, you shrug and say, “I don’t know how, but it seems to work!”

Despite Taylor’s admission that he had next to no mathematical evidence to support the accuracy of his formula, that didn’t stop him from claiming it was a more reliable measure than calculated energy. “My figures give a surer and more accurate indication than do the figures for mathematical energy.”

Taylor’s TKOF also fails to consider a number of variables that are essential to understanding the behavior and impact of modern bullets, such as a bullet’s design, composition, sectional density, energy, and expansion. It skews blatantly in favor of heavy, large-caliber bullets—no surprise given Taylor’s known affinity for such old-world behemoths as the 450/.400 Nitro-Express—downplaying the importance of velocity. “Theoretical, mathematical muzzle energy lays too much stress upon velocity at the expense of bullet weight; whereas my figures permit the heavy bullet to come into its own in spite of its more moderate velocity.”

One can quickly see how skewed the math is when comparing two similar cartridges of different bullet weights. Take the .30-06 and .35 Whelen, for instance. The latter is essentially a .30-06 necked up to accept a .35-caliber bullet. The former, launching a 110-grain round at 3,400 FPS, scores a modest 16. The .35 Whelen, firing a 200-grain round at 2,700 FPS, scores a substantially higher 27. But is the .35 Whelen really nearly twice as effective at delivering this “knockout blow” to which Taylor refers while traveling 20 percent slower?

Using the formula today

Applying the TKOF to big-game rifle cartridges, and specifically to their “knockout” effect on game the size of elephants, may have some validity. Very few hunters in this era could confidently corroborate or refute Taylor’s formula given the exclusive and expensive nature of hunting dangerous game. As far as street cred goes, we can’t diminish Taylor’s experience in the field. By the time he wrote this book, he’d been hunting 10 months out of every year for more than a quarter century. No doubt he’d taken enough game to draw some reasonable conclusions about the effectiveness of various rifle calibers and platforms.

The issue is that his formula often gets thrown around as a reliable means to rank the overall efficacy of rifle and pistol cartridges, typically outside the context of hunting large, thick-skinned game at close quarters. Taylor himself dismisses this application of his formula. “I am fully aware that many ballistics experts would look very much askance at these figures, but I do not care because I do not pretend that they represent ‘killing power,’ but they do give an excellent basis from which any two rifles may be compared from the point of view of the actual knock-down blow, or punch, inflicted by the bullet on massive, heavy-boned animals such as elephant, rhino, and buffalo.”