I agree. A good washout with any decent solvent is all they need. And that's just to get rid of any thick grease preservative and the very rare machining chip left behind. Spray brake cleaner, carb cleaner, alcohol, white gas -- whatever. Do it outdoors if what you're using has vapors.
Your case lube will serve as rust preventative after use, so no need to apply anything special. (I highly recommend Imperial Sizing Die Wax used VERY sparingly.)
This!
