One thing Dr. Gaddy used to recommend was Behlen's Spray lacquer, in gloss. Pt # 101-0800. After cleaning ALL oil etc.off just spray on. Several light coats are best. I've found it is easy to use, easy to reapply or touch up. I generally apply wax on top of that, but mostly because I wax the whole gun anyway. I got one spray can from Woodworker's Supply via mail over a year ago, and have done about 6 guns and have plenty left. I would recommend against any bake on lacquer finishes as touch up or removal would be a real bugger. I this stuff isn't to your liking just wipe off with acetone.
Frank