Butcher's Wax would be good. I use Johnson's paste wax.
I usually give a good scrubbing with a rag dampened in hot, soapy water after hunting season, wipe the metal well with B.C. Sheath or CLP Breakfree, apply a few thin coats of the Johnson's (yep, metal and wood), and then, throughout the year, I wipe the metal down with B.C. Sheath and rub beeswax on the everything and buff it up with a cotton cloth. The beeswax gives a less shiny appearance than the paste wax.
It's better to have a couple very thin, very thorough coatings of wax than a gloppy, built-up thick one. Put a dab on, rub it in well (rubbing hard enough to melt it in) and repeat.
Be warned that with some stain-in-the-oil finishes the finish may be lightened in some spots with repeated rubbings. You can work this to your advantage if you want a "handled" look of age to the gun. Clean it up, oil the metal, wipe on just a bit of fresh stain (I use Laurel Mountain Forge from T.O.T.W.), let that sit overnight, and then do the wax rubbings. This builds up the the cracks and corners but has a lighter tone in the level "proud" spots. If you're fortunate enough to have carvings or other features it highlights them and makes them stand out visually.