I know the last site, gunbuilds, has instructions for home builders. The first two sell completed receivers but have some templates with orders, they may provide you with some info. TEC Tactical can be impossible to get a hold of. I tried ordering a completed receiver from them, but they never got back to me. Guess they hate money.
Wilhelm, I got the idea and desire to have one from your thread. Greg told me he is accepting new work, but as stated, TEC never got back to me about ordering a receiver. I also want to SBR it before sending it off to him. All I have is the kit so far. I don't need any more guns of any type, but I really have to step up my SMG game, even if they are just semi auto repros. I'm about to fill out a Form 1 for my semi Action Arms Uzi.