On my stainless handguns I spray the front sight with flat black...over-spray hurts nothing. I mainly shoot steel targets painted flat white, so the flat black contrasts well. When I used to deer hunt a few years ago, I used white "Testors" brand model paint. I discovered that most of the deer would show up about dusk, a dark front sight would not show up against a dark deer, even if there was snow on the ground. Sounds strange...white paint on sights for deer in the white snow, but it worked.
Also, I discovered that spray sight black would rub off in the holster...spray paint did not.