In tropical climates many of the Weatherby cartridges, (as well as the .416 Remington), are prone to suffer from excessive pressure. The operating pressures of all of these factory loaded cartridges are maximum...and when coupled with really high temperatures encountered at times in Africa....they have developed reputations - less than favorable - with professional hunters on that continent.
The .416 Rigby, with its extrodinarily large case compared to ballistics, was initially loaded, (and continues to be loaded), more conservatively and does NOT have problems with excessive pressures in Africa' s heat.
For more info go to:
http://www.african-hunter.com/lessons_learned.htm
The .375 H&H also has a good record of " behaving" itself in tropical climates. Because it too was NOT loaded " to the gills" by the factories.
As you will note in the article that Weatherby cartridges behave themselves when handloaded down to allow for the increased heat of Africa. I don' t know for sure...but I suspect that any ammo loaded by " A" Square would be just fine, (Weatherby or not)!
I can' t personally attest to these problems because the vast majority of my experience is in either temperate or cold climates. But I have heard and read enough, (from people I trust), that some cartridges, (as loaded by factories), are prone to high pressure problems...because of their NORMAL operating pressure! Whether you would choose to give merit to this information or not....is a personal decision!
Good luck!
P.S. I have not shot a .460 Weatherby....but have shot a .50 BMG....both rifle and machinegun!