For an RG that's pretty decent looking - I had always heard that RG stands for Rotten Gun. Maybe I'm missing something but I don't see anything that looks like an adjustable rear sight. Maybe if you posted a view of the top?
Also, it looks like the screw through the frame above the trigger has backed out some, might want to tighten that before it gets away.
I too am guilty of owning an RG, but in .44 Magnum. Who'd have thought that such a thing existed?
Model 29-2 and its Spanish, American and German cousins