It's not a shooting league per se, it's just a monthly match that's run by a few people involved in this particular "league". As far as I know, the NRA range is one of the only/few places that have sponsored matches, but it's run similarly to IDPA, USPSA, etc the only difference with those leagues is you have pay each year to member, and pay for each match. With KSTG you just pay a match fee, and they have shooting tests for rank 3 or 4 times per year. Right now I'm a C class shooter, i think it goes D,C,B,A,Master, Grandmaster, similar to how other leagues are set up. I got my ranking the first time I ever came out to shoot, shooting in Khakis, button down, and my lunargrands cuz I left m change of clothes at home. So im pretty sure the next time theres a qualifier, I'll make B class.
There's not a lot of info on it outside of pistol-forum.com, but here is the website link
http://kstghq.com/rulebook/
If you have a local IDPA or USPSA club, I'd definitely go out just to see how you can shoot against a timer. It's a lot different when you have to move, and think and shoot. Plus it's a lot of fun, and most of the guys there a decent people. I think this summer Im going to try out IDPA since there I know there's a local club in MD that has matches during the week.