I have seen that Harnmaster was pretty detailed (picked up the core rulebook at an auction a few years ago), but I have only seen references to Gunmaster.
Was Gunmaster an official published release?
Did it update things beyond combat like the Occupations tables for a more modern setting?
Currently both sites that seems to have links related to it are down.
http://www.Warflail.com and
http://www.lythia.com/forum/
I would be interested in anything you would be willing to share.