These guys are 100% correct! KE is NOT a reliable guide to killing power! Neither are the myriad other schemes various people have invented to allow one to caluculate what is necessary for clean kills on various species. I include such theories as John Taylor's "knockout values", Elmer Keith's "pounds-feet", etc., etc. in this category. There are just too many variables involved! Bullet construction, shot placement, bullet diameter, impact velocity, bullet weight, sectional density, and even whether or not the animal is relaxed or hopped up on adrenalin when the bullet lands, and other factors as well, all influence what happens.

The only value there is to any of the calculated indexes of bullet power is that the figures allow you to compare cartridges using bullets of like construction. Once you start using these figures to decide whether a given load will reliably kill a given kind of animal or not you are enroute to a smare and delusion! For example, if you compare two different 7mm cartridges firing a Remington 175-grain Corelokt bullet, one of which produces 3000 foot-pounds of energy and the other a mere 2000 foot-pounds, one might reasonably conclude that the one carrying the higher energy level would be a better killer of, say elk or moose, than the other load. In fact, it is entirely possible that the velocity needed to get the 3000 foot-pounds is too high for adequate penetration due to bullet construction, and that the load having only 1500 foot-pounds actually performs better on the elk or moose!

There is a book by Bob Hagel called "GAME LOADS AND PRACTICAL BALLISTICS FOR THE AMERICAN HUNTER" Get one!! It will answer your questions about killing game animals with a rifle! Probably the best, "FAIR AND BALANCED" treatment of this subject ever written!