[saxman]

That's not a stain on the frame - it's just 'browning'. I recommend 'Clenzoil' for old guns. Use it on everything within and without, including the wood. Take the grips off and clean them with 'Clenzoil' on a toothbrush. Here's how to get them off safely; remove the magazine - using the correct screwdriver, remove the grip screws, and note which side they came from - work the RH side grip loose and remove it - carefully work the LH grip loose by very gingerly pushing on the center of the grip from the RH side, thru the mag well - pay particular attention to the little point of wood behind the safety cut - it will break off if you look at it wrong - they usually break when you try to pry the grip up from the bottom. Once you get the grips off, examine the reverse side for markings, and photograph them. Clean the grips on both sides just enough to get the soil off. Don't worry about too much 'Clenzoil' soaking in - it won't permanently darken the wood. Blot loosened dirt/excess oil from the checkered side with a piece of terry cloth - finish the checkering by brushing with the dried toothbrush. I definitely never use water or detergent on gun wood.