I just picked up a 1970 marked "sneak" M39. The bluing/blacking is 98%, the bore looks brand new, and the wood appears to have no finish at all. I intend to shoot it periodically but want to maintain the correct finish on the wood for historical and collector value reasons. Googling around, I find that there are two schools of thought on how to care for the wood. One is to do nothing at all. The other is to treat it with the 1/3 Tom's beeswax mix. I live in a very dry area and tend to over-rather than under-oil my guns because I like to preserve them. Any suggestions on how I can keep this stock from drying out without ruining the unfinished look of the stock? Would RIG gun grease work? It seems to be very inert and natural-ish. Thanks

I cannot believe you pick up such an awesome rifle- I want a 60s or 70 M39 myself- and not post pics!

My first choice would be to do nothing at all.  However, if I had to do something to it, I'd use either Tom's Pine Tar Mix or Tom's 1/3 Mix.

http://www.thegunstockdoctor.com/Products.html

His Pine Tar Mix is close to what the Finns originally used on most of their M39 stocks.  (The ones that were finished, that is.)  However, that will darken the wood somewhat, similar to the wartime M39 stocks.  If you're wanting to keep the light, unfinished look, then the standard Tom's 1/3 Mix - which is made with BLO instead of pine tar - would do a better job of that.

why touch it when it doesn't need anything.

Boiled Linseed Oil . At least a 75/25 mix with mineral spirits.

The postwar Finn M39 stocks esp the new ones are very dry and prone to cracking. If you want to shoot it get some moisture back in it first.

Take the rifle down including butt plate, with 1" paint brush liberally apply on BLO to stock inside and out paying special attention to inside recvr inletting area letting it soak in. Wipe off excess doing at least three coats to inside of stock.

this. or even raw linseed oil

Tom's also makes a pine tar finish for Finn rifles. I've never used it but folks that have seem to like it.

That said since the rifle never had any finish I'd be inclined to leave it be.

Another vote for just leaving it be.

I would ask this question on gunboards. They are fanatics over there, to the extent of importing finnish oil.