I am currently looking at Quick Detachable Mounts for a FN Mauser in 458 Win Mag and 375 H&H? I didn't find anything for Talley? Leupold has some. Does anyone use the Leupolds? Your thought's. They will be going to Africa.

I've used the Leupolds for years on a 375 without any trouble. 458s are hard on scopes and mounts though.

I'm a big believer in 8/40 screw holes for the bases on big kickers. I would call Talley and talk to Gary Turner. I would be surprised if he can not help you. You will need to accurately measure your screw holes spacing before you talk to him. I sheared the base bar off the bottom of a Leupold QRW ring and switched to Talley on a 458 Lott.

I neglected to mention that I also used the larger screws in mounting my scope. I hate those dinky little screws. In fact the main reason I like Rugers is the scope mounts.

I have Talley's on my Mark X .375 and .458.

Talley certainly makes them as I have 6 or 7 sets on rifles as we speak, both 30mm and 1 in. rings. The FN and Mark X use the same ones. I have had the Leupold, worked OK, but not even in the same league. I have broken some of the flimsy levers off the Leupold, so went to Talley and never looked back.

Just order a set of Tally QR rings and bases for my Browning Safari grade 458WM which is a Mauser.
I have them on 3 other rifles (375 Weatherby, 416 Remington, and a 375 H&H). Never a problem!