Adams Arms is out of Palm Harbor, FL. Their address is an industrial park just off the harbor. The same address applies to a bunch of distributors and importers so it wouldn't surprise me if most of their parts were sourced from South America (a'la' Taurus). See lots of good reviews on their piston kits.
Brad
Palm Harbor is semi local to me, and I've met the guys that run Adams Arms at several gunshows around here. They've always been cool, willing to talk and answer questions, and generally guys I wouldn't mind giving money to. I've seen pictures of their machine shop and they say that the piston kits are made almost entirely in house. They also sell a bunch of stuff at their tables that is obviously a resale of some kind.
I don't like piston AR's at all, but if I was going to run one, Adams would probably be the kit I would run.
FWIW the piston guns that SPikes Tactical puts out are Adams kits.