I spent 8 years as a wood finisher before moving over to the CNC programming thing so I know my way around that kinda stuff. started out with LOTS of lacquer thinner, sanding,naptha, sanding, acetone, and MORE SANDING. the stock had 50+ years of gunk soaked into the pours so sand, sand, wipe with thinner, sand sand, more thinner. lol I had to water steam half of the stock just to get all the dents and stuff out and then re-sand. dyed the wood, stained it, and sprayed the stock with a commercial product we use to spray conference tables. stuff is amazing. it turns almost into a plastic when its dry. very happy with how it came out!
as for the question about the Cosmoline.....kerosene is the best stuff. soak the whole gun (in parts of course) in a tray of kerosene for a few hours and the cosmoline will literally drip right off. (just keep flames away for a bit!! lol once thats done take the gun out and let it air dry for a few more hours. (kerosene drys like a film) once thats done I just take hopps 9 and clean the crap out of it. wipe it down with oil, put her back together and go shoot something!!!