30mm one-piece adjustable rings? All searched-out.

Alright, I searched this forum and google. ARE there any one-piece rings adjustable for elevation and/or windage for 30mm scopes?

Looking for something like the BSA mount from Pyramid

http://www.pyramydair.com/cgi-bin/accessory.pl?accessory_id=1816

Is it that the adjustability makes for a mount considered too weak for a rifle that would take 30mm scopes?

I want to adjust the mount, not the optics.