Several options:
GunKote comes in gloss black (2400 series). Also comes in midnight black, a very attractive color that looks surprisingly like bluing.
http://www.kgcoatings.com/firearm-co...cts-page-2.php
Brownells sells bake-on finishes.
http://www.brownells.com/.aspx/pid=1...URE-GUN-FINISH
Brownells also sells the Durabake finish.
http://www.brownells.com/.aspx/pid=4...-FINISHING-KIT
Brownells sells their Baking Lacquer finish.
http://www.brownells.com/.aspx/pid=2...LACQUER-LIQUID