With hardwoods, I like to finish a gun just like I finish a bow. A friend gave me a good tonic to rub into the wood comprised of linseed oil, turpentine, and acetic acid (vinegar). I usually mix it at 50/25/25, but it's inexact, so I'll just get it close. I rub it in every day for a week or so, letting the wood dry in a cool, dry place. Then I'll hit it with another coat once a week for the next couple of weeks.
Here's where it gets wacky: You're going to need an antler. My rubbin' horn is deer, but I suppose anything with a solid core would work. Find a nice flat area of the antler that will lay down across whatever area of the wood you're working. You want to get as much surface area in contact as you can, lest you gouge the wood. Then, you rub it. Mash on it firmly, and always go with the grain. The amount of polishing will determine just how shiny the wood gets, so you'll want to check it in the sunlight lest it become too reflective for your tastes. The rubbing part is an acquired skill, so you'll want to practice a little bit to get your technique just right.
Done properly, the wood will take on a nice warm glow, have a silky-smooth finish, and will resist water like polyurethane. I apply this finish to every wood knife handle I make. This kind of finish is not for everyone, as it is quite time consuming. It also works best on dense woods. Cherry and Walnut seem to love this finish, but I have used it to some great effect on beech as well.
