4140 steel for barrels or 4150 steel if you want mil spec 1020 or 1520 steel for components that experience lower stresses, such as trigger guards and sights. 6061 aluminum and 7075 aluminum for receiver / frame all states allow for anon to mill and lathe their own firearms via 2nd amendment even the atf says so > no, a license is not required to make a firearm solely for personal use.
United States