Are you going to coat the gun with a colour? Sorry to edit this but if you are going to consider coating the weapon with a camo finish I might be able to help you with the product. It is called Duracoat.
I have seen examples of guns finished in duracoat. Excellent finish and very durable.
This Company can supply.
http://www.caswelleurope.co.uk/Paints_Coatings/Duracoat/duracoat_firearm_finishes1.htm