Unless I'm mistaken, the RS2 is an AR1000 variant. IF that's the case, than I imagine it will fit into the stocks of most the other AR1000 type guns. That list would include (but probably isn't limited to):
The Norica Quick Gold (what the AR1000 is based on; might not have the name right), TF89, Hammerli Titan, Walther Force 1000, and a whole slew of Beemans: SS1000, GH1050, Bearclaw, Elkhorn, Heavy Target, Mach 12.5, RAM Air, Teton, Silver Sting
I'm not totally sure about that mob of Beemans starting from the Bearclaw, but I'm fairly confident. Of course, even if they are all the same action (AR1000), I suppose that doesn't guarantee a fit. And I don't know for which of them you can order a stock either.
Just listing some possibilities.
