Ive found that WD40 is not the best on bluing so i avoid it now if possible. If removed quickly its probably fine but when you can get good mil-spec CLPs for less in a gallon, i dont see any need for WD. It also seems to have issues with Nickel finish and can leave a stain or dull it over time. On bore rust, there are also better options IMO.

I use silicon based cleaner/polish on my motorcycle stuff and it works great to make water bead right off. I spray it on a soft cloth and let it dry a little bit then give it a good wipe down. It is nearly scent free too once dried.