Gentlemen,

Being primarily a mountain hunter I haven't Africa safari great experience and I must confess that I had never done elephant …or other game culling.
However, with the help of age, I know some things about repeater rifles.
In my opinion -and for that particular use- the best ever made action is without contest the Original Mauser magnum, the No.19 or No.20 specially built for such caliber as the .404 Jeffery (10,75x73), .416 Rigby or .505 Gibbs.
I know that many clones are offered today, but even the best ones, as provided by FZH for example, are not up the same quality than the old actions made at Oberndorf.
Perhaps the best modern made systems of that kind are those from Mayfair Engineering, machined from hammer forged 8620 nickel-chromium-molybdenum steel blanks.
Second would be the brave Brevex mod.400, very tough and reliable action, perfect to build a .416 or a .505.
The post war Mannlicher-Schönauer magnum is very slick with near perfect feeding, however the original stock is horribly unsuited for recoil control and the sights, small notch rear blade and tiny bead, don't permit quick shots.
Notice also that on this action fitting a scope with a quick and easy detachable low mount could be a real headache!
I like very much the pre-64 Winchester 70' and I consider that such a rifle chambered for the .458WM and fitted with a deeper magazine would be almost perfect for the job.
Regarding the BRNO and CZ the ZKK602 is my first choice and having committed some .404 Jeffery working rifles on that action I can certify that it's extremely sturdy and reliable.
The 550 is not as good and need much more work to qualify in the same class.
Now you must also consider the fine FN built 98' actions that, even of not C type, were of nice quality. We have tested these actions on .404 and .425 W-R rifles originally made at Fabrique Nationale, Herstal, and the only trouble with them is their reduced magazine capacity. My son has built a .458 Lott on ones of these actions, fitted with deep believed magazine, and the rifle performed flawlessly and fed reliably with either .458WM or .458 Lott rounds.
I haven't advice about the Zastava used by the "Withworth" named Interarms rifles of the eighties but here these Yugoslavian Mauser clones don't benefit of particular interest.
Notice also that the wartime Mauser actions, and particularly the BYF42, if they aren't very well finished, are a good basis to build a .458WM working rifle.
Indeed, all the above, is my own observation and I'm sorry for my bad English, hoping it will be understandable…certainly more than my perfect French !

Best to all.

DORLEAC
www.dorleac-dorleac.com