If you've not used/mounted the 1" rings that came with the gun, Ruger will exchange them for 30mm for no extra cost (other than maybe shipping.)
I bought a set of Warne Quick Detach 30mm rings that I can't use if you might be interested. The reason I couldn't use them is that the saddle of the UltraDot 30mm that I wanted to mount is only about 1mm too wide so that the rings wouldn't work. Unfortunately, the rings weren't cheap but they're not of any use to me.
Here's what they are:
http://www.opticsplanet.com/warne-30mm-medium-matte-quick-detach-ruger-77-rings-54258.htmlWhat I ended up doing to mine was add the Weigand SRH+ Mount and use regular 30mm rings.
http://www.jackweigand.com/srh.htmlBut it does eliminate the use of the fixed sights.