If ypu want to keep original patina use a rag lightly dampened with mineral spirits , then apply BLO.
If you want to do a complete strip to bare wood,then stain everything so all the wood matches and refinish I have a method that works very well. I have refinished over 30 Garand stocks and many M14 and several carbine and 1903 stocks this way.
Takes maybe 10 -15 minutes for a completetly clean bare stock . Its a really simple ,easy and alot less harsh than other methods
I first take Purple Power degreaser full strength and put it in a spray bottle.
I then spray down the stock with full strength degreaser, immediataly you will see years of grease. oil and dirt start to roll off. I do this in a utility sink but you can use a buckt etc.
I then take a soft nylon bristle brush and go over the stock.
Rinse well with hot water while rubbing with brush .
I will usually do procedure one more time except the last time wipe dry with cotton towel.
If stock is very oil soaked it may take another cleaning .
I then let the stock set to dry out of direct heat source.
This is what the wood looks like after drying