I don't know why people mess around with an adapter when they are just going to build their own reg to use with a paintball tank. They do make 1/4 NPT to paintball tank fittings.
Check it out:
It just seems like I've read so many folks having issues with those cga-320 to paintball adapters. (operator error...) With this, you just screw the paintball tank directly to your reg.
(please forgive my beat-up hands)