I have the later 80's version, the RG40 in .38 Special. If the gun checks out by the usual revolver standards (not pitted and corroded, chambers line up with bore straight, timing is correct and lockup is ok), then keep it and shoot it with whatever you want. My gun handles +P just fine, no signs of wear after a few hundred rounds plus a thousand or more of standard pressure stuff. The major stressed parts of the gun are either steel or thick enough zinc alloy that you wont harm them by shooting the gun. IF you want to play it extra safe, keep to standard 130gr FMJ or 158gr LRN for practice, and buy Federal 125gr NYCLAD hollowpoints for defense (if the gun works well enough to count on. Mine does.)
You will wear springs and possibly some internal parts after lots of shooting, but the gun isn't collectable or worth much unfired anyway, and if you want, you can get most parts you might need at Numrich.
*EDIT* Hmm, post from May it seems. Oh well.