I hope they remember at least half are Fed Gov agent infiltrators. If I were a member I would start offing the other members. You got better than a 50/50 chance of offing a traitor. I would pray the “mistakes” would forgive me.
No need for that. Start with the people you know, your neighbors, and keep it local. Surprising how strong controlled growth can be.
In small rural close knit communities, I would think that they wouldn't be prone to trust outsiders.
I'd hazard a guess that many militias are comprised of people who have grown up together and know each other well, enough to trust their lives with.
I'm sure they are well enough aware of the fact that infiltrators will come along and are prepared to deal with them.