To paraphrase Ganyana´s own words in the article - the .400s are the dividing line between hunting rifles and stopping rifles.... A hunting client does not need a stopping rifle. This is the reason why he recommends the .400s (.500/.416, .450/.400, .404, .416, etc) as the ideal rifles for hunting clients, accompanid by a .375. He also stated, however, that hunting elephant cows and in thick bush required a stopping rifle and that he used a .404 and a .450NE as stopping rifles. However I take that with a pinch of salt because pretty much all the advice (including recent books by Harland, Nyschens, etc, etc) suggest that the .404 was not powerful enough for elephants in thick bush and that serious elephant rifles start with the .450s. I think this also relates to the type of country where they are hunting - in more open country, the .416 may be more suiable (Selby in Kenya springs to mind).