God damn, there is a search feature, USE IT.
I've seen three 'painting gun' threads in the last few weeks, if you took the time for look for them, you wouldnt be wasting this tiny bit of forum space.
Krylon works, any paint works as long as it doesnt reflect the sun, which is very exposing.
Be sure to clean your rifle, sand and prime it, and apply in small layers, Take your time with it. After you're done, let it sit in a warm place undisturbed for a week so the paint can settle in.
(edit: For cadpat. Use painters tape and a fine exactoknife to create a stencil.)
This was done with paper stencils. Not worth the time.
________
FIX PS3