I hope I didn't screw the stock up on my Enfield.
Here's what I did.

Set the stock in the sun for a couple hours in 90 degree weather.
Checked on it every 10 minutes to wipe Cosmo off.
I then took it inside and put Dawn dish washing detergent all over it and scrubbed it good with 0000 steel wool. Rinsed with HOT water while scrubbing.
Man, I've never seen so much dirt and crud coming off a stock.
I then set it back in the sun for another hour to see if more cosmoline would sweat out.
No more came to the surface. Next I'm going to try and raise some dings with steam.

I'm going to 0000 steel wool it until slick and apply BLO as described in another thread.

Here's what the stock looks like now. The HGs above it are in good shape compared to what the stock looked like before.