KG Guncote works well. Be sure to lightly sand blast first.
Be sure that YOU do the machining. IF you do not you may get yourself and the machinist in trouble. You must also mark it per federal guidelines. I do not know Oregon law, if it is like California you may want reconsider your project. At very least stop posting about it on the internet.
Mmmmm, NO.
So you are saying a gunsmith with FFL can take possession of a modern firearm or finished lower manufactured after 1968 without a serial number?
Please highlight where I said that. A private citizen can manufacture a firearm (pistols/handguns excluded) for personal use. You can't manufacture firearms for sale or trade. The ATF says said individual should serialize or otherwise mark a personal made firearm for identification purposes but it isn't a requirement. What a FFL can or can't do is irrelevant to me.
