I own a Whitworth in .458 WM and am not enamored with the rear sight base - seems like it will be very difficult to retain zero afetr removal and reinstallation of the scope. It's a Leupold windage adjustable model "STD" two-piece. Please see pics below:


I'd rather install something like the Leupold QR or QRW mount systems, but am not sure they just bolt right on.

Are the Whitworth's already drilled/tapped in a standard configuration?

Yes.

If you are looking for bases, the MK Xs are sometimes listed under Mauser in catalogs

If you can't find the Leupold QR bases for your Whitworth, the older Redfield's originally had the right hand screw coated with thread locker. It used to be standard practice to rotate the scope "ON" counterclockwise and rotate them "OFF" clockwise; this was in the earlier days when folks didn't trust scopes yet. The manufacturers and the public have pretty much stopped mentioning routinely removing the scope. Once you get a good zero remove the right hand windage screw from the base and coat it with your favorite flavor of Loctite, reinstall it tight and from then on remove using the left hand windage screw. Also it use to always be specified to intially mount and dismount the front rotary dovetail ring with a wooden or metal rod the first time to keep from bending the scope tube. Another lost art I guess! Buy Talley bases or find and old Jaeger or G&H detachable sidemount are other options as well.

+1 to that! Good advice that still holds true today.

If MKX is not listed the Mauser FN bases are the same.