I have an U/O Baikal, which has the same rail, and I used standard .22-style (3/8") ringmounts from Lynx, but with lever release screws so I can remove and replace the scope (a 4x Leupold) by hand. I butt the front ring up against the stop at the front of the dovetail for reasonable repeatability.

I would think the same would work on the SxS