I have a friend at work who has a machine shop. If I buy one of these 80% lowers and give it to him along with 20 bucks to do the milling for me, does that legally constitute a ‘transfer’? Even without a serial number?
If your friend does that for you, he would be in big trouble unless he is licensed as a manufacturer. YOU can make your own firearm legally, though I think you may be required to mark and serialize it. And you cannot sell or transfer it.
Just buy a used 100% lower receiver from a private party. No background check.
That is the question. I suppose it depends on the DA/prosecutor and where you live.