I did this as part of a set of small pistols for a friend of mine a few months back.
She had this one and a Doublestrike that she wanted painted with a theme inspired by an old derringer in a display case in her childhood home. Because I am so terrible at documenting my own work I only have a picture of this one.
I learned a lot about masking and using a lighter touch with the spray paint. It might be worth investing in an airbrush at some point.
I really do things other than paint Nerf guns. I really do. It's just that I've been doing a lot of this sort of thing recently.
If you want proof of the things I've done that don't involve Nerf at all you can check out my Deviant Art page.