In episode 11, you asked about / mentioned ZERO. I am not a member of any of these groups, however our family attends “con” events, visioncon, comiccon, planetcon, trekcon, you get the idea.
In the Missouri area ZOD is popular both at the “con” events and at certain ranges, they seem like nice people. There was a group in the Springfield Missouri that was another Zombie Defense group, but I only met them a couple of times in 2011 and 2012.
Just this week a friend has introduced me to ZERT (ZERTNation.com), it appears they have training and more but I have not met with them in person.
With that said, as “cosplay” and as people to sit and drink sweet tea with, they the people I have met, seem to be “good people”, other than that I am hoping by starting a forum topic a few other with more experience will jump in.