Taylor never intended that his famous TKO values be use for anything other than rating a bullet's effect on knocking down large, thick-skinned game like elephants, rhinos, hippos, etc. It was not a rating of killing power on thin-skinned game, and those armchair hunters who use it for that purpose are kidding themselves if they think that it is in any way a reflection of Taylor's lifetime hunting experiences.
The fact is that he thought that kinetic energy was as good as anything for predicting the killing power of bullets on lighter game. Who knew? :roll:
As for Ruark, IIRC in his famous tome Use Enough Gun he devotes less than a page to the choice of hunting firearms, the rest of the book, while interesting, has little to do with "using enough gun.