I'm assuming you're talking about a G36, since that's your avatar picture, but you may want to poont out what you're talking about, if you want people to help you.
There isn't really a "spray" to protect paint... in theory you could clearcoat it, but that wouldn't be very desireable. If you really do find the paint wearing away, you can always re-apply some yourself later. This really isn't a big deal though...
aka the fully recovered airsoft addict formerly known as HonestJohn
Igitur qui desiderat pacem, praeparet bellum.