Cooperville Part I:

[.45cultist]

I might go to an earlier idea, almost modern weaponry(1920's-1950's) with less modern transport(1890's). M1911's and AR rifles with wagons and horseless carriages. Crystal radio receivers, early 1920's style generators. I now think it would take a few communities, perhaps a county or two. Like the dark ages, low population is the main inhibitor.