Check this guys Duracoat work out...
GoldenLoki.com
He mainly does plastic pistols, but I see a Colt revolver in his gallery too. Hopefully, he can answer your questions. Haven't done any duracoat myself, just thought I would pass the link on. Good luck.
Inspector - Nice sketch. I'm an artist and a lurker here as I enjoy shooting too. I decided to register to coment on your drawing and to be able to post in the future. One minor suggestion, erase the top of the cylinder to show the highlight, it will then match the barrel and add a little more...