Damn you guys get too complicated with this stuff!
I took a can of freakin' paint, grabbed my gat and went at it in the backyard. Yeah, I painted my lens caps. Did it chip off? Yes, and it looks badass! I also got some on the trigger and grips. It wore off, but I didn't waste any time masking and all that crap. All I had to put tape on was the "lenses" of my PEQ-2. I took off 2 of the rail covers so I could get the rail underneath, but left my accessories on so the pattern matched up.
I thought about doing what you guys said but after I thought about real circumstances, like being in a combat environment, I realized the "rough" look was what I was going for. As the paint fades and chips off, it just gets better!
With painting guns/gear, the more you think about it the worse it looks!