Most any decent stock finish thinned out a little and applied with a small patch.
Dampen the cloth patch with the finish, you don't want alot onto the surface. Wipe it accross the metal in long even strokes. Quick enough to avoid any overlap lines but effeciantly enough to avoid missing any spots.
Tru-oil will work,,though I personally have a dislike for the stuff!,,just me,,.
Any of the in the bottle clear wood finish products will work. You're just putting a thin clear protective coating over the metal,,nothing else,,nothing special.
If it gets onto the wood a touch,,wipe it off as it won't dry all that fast.
When it does start to wear, either go back over it with the same mix to sharpen it back up. Or if you like, remove what's there with acetone and recoat.
Be careful using the acetone on the assembled gun as it will remove most any existing wood finish.
I don't like the lacquer type coating for the same reason most don't like them on wood. They're kind of brittle and they crack, chip & scratch easily. Plus they dry so fast, it's sometimes hard to get a nice even coating down w/o over lap lines.
Same with shellac,,the old stand by for case color protection.
But shellac dries a little slower so a neater job can be put down with it. Doesn't wear well though.
I try to keep it simple. No spray equiptment or E-Z Bake ovens to apply a coating like this.
