Ray, You know I am interested in this stuff and I would love to hear your first hand accounts of the 458's failings and the details as to why. Is it possible that any of the loads you saw fail were old and/or factory ? Have you actually tried any AA2230 powder in the 458 ? It works wonders in my experience and tales of acheiving 2300fps are not exagerated.
Finn Aagaard always claimed that most of the 458 bashing was due to hunters blaming their ammo for their poor shooting. Currently Don Heath, Charlie Haley and Mike LaGrange, who as you know, are three of the foremost ballistic experts in Africa ( with many years and many thousands of elephants to their credit) claim that the current 458 Win is one of the best elephant cartridges.
Elephants and buffalo are not my field but I can verify that good 500gr bullets @ 2100fps drops big bears with the authority of a crane falling on them.


Phil Shoemaker
Alaska Master Guide,
Alaska Hunter Ed Instructor
FAA Master pilot
www.grizzlyskinsofalaska.com

Anyone who claims the 30-06 is not effective has either not used one, or else is unwittingly commenting on their marksmanship.