This video discusses what to do if law enforcement, i.e. ATF, shows up at your door. You have rights and you need to know what they can or can't do. "I am not a lawyer and this is not legal advice, just my opinion."
You must always be on your guard to keep out government intrusions.
So are they doing this with all gun parts suppliers and manufacturers?
This is completely and utterly unconstitutional. To bring pressure to bear between sellers and buyers in order to build a list of potential gun owners is only meant to do one thing. To make a list of guns and or parts for confiscation.