I researched different gun finishes a few months ago. I came to the conclusion that ceramic coating is about the best you can get. The stuff is called CeraKote. The NIC Industries web site has pictures posted of the different colors and you can see the difference between satin and gloss. The oven cured is obviously better than air cure.

http://www.nicindustries.com/Page.asp?NavID=501

http://www.theshootersroost.com/svspricing.html

http://www.larsontactical.com/id27.html