Oh, I see, I hadn't gotten eyes on the specific pistol you were talking about yet. Ruger should sell proprietary rings for that. I imagine if you stretch your Google Fu, you might be able to track down a picatinny adapter for it :\

*edit* BAM! http://www.brownells.com/optics-mou...er-to-weaver-base-adapters-prod1721.aspx

I don't know about the strength of using just one of those mounts with a SPARC though. The SPARC II is light, but it's not ittey bitty like a DR Optic. That much mass flopping around on top just doesn't seem like a good idea, .22 or not. In that case I would recommend a Burris Fastfire II or III for best results. I could be wrong though, I don't have personal experience with it sooo...

But since it doesn't have a Pic rail without adding a bunch of stuff, I'd say search for an older model aimpoint maybe? The older versions (Comp M2 Gen and earlier) in their hunter variations use two 30mm rings, so that may work.