While I am a huge Tung oil fan (I use more of it than anything else in my shop, hands down) I wouldn't use it on that stock. The original finish is undoubtedly Linseed oil, so I would do a version of what rtaylor said above.
Use a chemical stripper to remove any oil/finish thats on it.
Use steel wool only....no sandpaper. If there are dents, steam them out (wet rag and a soldering iron)
Once its clean and smooth, wipe it down with lots of distilled water (melt snow or empty you dehumidifier for a cheap and easy source)
Let it dry, sand off the "fuzz" that occurs with more steel wool...then repeat.
Lay on a bunch of BOILED linseed oil (not raw), let it soak in for 30 min, wipe off, then let it sit overnight...repeat. For the first coat, thin the BLO 50% with mineral spirits.
For the final coat, apply another thinned coat (50%), allow to sit for 10-15 min, buff off the excess and let it sit for a week. Give a light rub with 0000 steel wool, then apply a coat of decent furniture paste wax (minwax is fine), then buff the crap out of it. Once a year, give 'er another coat of wax....it'll look and smelll right, be historically accurate, beautiful, and durable (Hell...how many enfields still look good today? Yup....BLO).
Can't tell about the crossbolt...what's it made of/whats wrong with it? Let me know and I'll tell you how to fix it
