I know that the AR 15 likes a wet bolt, and we used to have one M60 machine gun in our arms room that seemed to run best when you poured straight 30-weight on the bolt between belts.
I've heard all the arguments, but I've never thought that a firearm runs best when it's dry. These guys take it to a whole 'nuter level.
That should put this particular myth to rest. Lube your firearm, please?