On second thought, putting Loctite (at least the blue stuff), on the screws might not be the best idea after all since the stock needs to be removed in order to clean the bolt, spring etc.
I would say this is the best idea. I have had my GSG-5 for a while now and have put many rounds through it and I don't recall having any issues with the stock screws on mine. I haven't noticed anything really get loose on it despite reading to the contrary on sites like ar15. com