Tried and True "Varnish oil" works. It is a bit soft, I think, for a good surface varnish, and could stand to have some more resins added. It does fine for an oil finish. And when the instructions say to apply it VERY thin, they mean it!!!! And, as always, it must be allowed to dry fully in the sun.
Apparently, the stuff is heated just enough to melt the rosin in it, but not boiled.
I have some of the oil/wax. I don't think it has any real application in gunstocking. I did finish a wooden bowl and spoon with it.