I have finished and refinished many of my rifle stocks.
My favorite is Minwax Tung Oil. This is actually their formula and it does have some varnish in it and some other ingredients that make it a bit tougher.
The key is in the preparation. Get your stock rough sanded down with 100 grit to get all the bumps and imperfections smoothed out.
Then go to a 220 grit and get it totally smooth. If there are ripples or bumps go back to the 100 grit and get them out.
Wipe the stock down or blow it off with compressed air. You want all the dust off so it does not clog the wood.
Get a good lint free cloth, a good cheesecloth works well. With a 1 inch brush put a good wet coat of tung oil on it, give it five minutes and then wipe it completely off. Let it sit for 24 hours.
The next day:
Hit it with 220 grit all over, wipe it clean, put another coat on it, give it five minutes, wipe it off.
Keep repeating this process until you have about 10 coats on it.
Now you can decide if you want gloss or satin for a final finish. If you want gloss, put a wet coat on it and let it dry that way. Sand it smooth the next day and repeat. In about three or four more coats (12 to 14 total) it will have a gloss that is just beautiful.
If you want to stay with a satin finish continue to wipe the stock down after each coat. Then go to a 400 grit paper and sand and repeat for the last few coats.
I have done all of mine over plain wood, no stain. However, if you want to darken it up more then just a few drops of stain in the tungoil will make it dark very quickly. Without the stain it will darken with every coat anyway.
There is religion over stock finishes. Many work just fine. But I would avoid poly in any form. I like the minwax because it is a little tougher than straight oil and it can be repaired with equal ease should you ding or scratch your stock.
