“YOUR ARMS RESOURCE”
According to the ATF:
What is an “80%” or “unfinished" receiver?
https://www.atf.gov/firearms/qa/what-%E2%80%9C80%E2%80%9D-or-%E2%80%9Cunfinished-receiver
Are “80%” or “unfinished” receivers illegal?
https://www.atf.gov/firearms/qa/are-%E2%80%9C80%E2%80%9D-or-%E2%80%9Cunfinished%E2%80%9D-receivers-illegal
What is ATF doing in regards to people making their own firearms?
https://www.atf.gov/firearms/qa/what-atf-doing-regards-people-making-their-own-firearms