There are a bazillion formulas for oil finishes, and an equal number of techniques for applying them. If you want to duplicate the oil finish as used at the Armory's and commercial factories pre-WWII, just dunk the thing in a pot of pure tung oil or boiled linseed oil (not raw linseed oil- it'll never dry completely), wipe off, and go forth and kill stuff with it. They weren't going for the very best finish- they were going for cheap.
