I don't know. I imagine they'll provide a list of gun purchases to local law enforcement, and require people to turn them into local law enforcement. I guess people will be at the whims of their local PD. Those areas with anti's in the local PD will probably receive a house visit. Those with a lot of guns listed as being bought will likely receive a visit from a SWAT team.
I sold a good bit of my rifles to in state residents. I might sell them all if the Biden's laws are enacted. So far, I am not required to keep a record of firearm sales, so I don't have any records of who I sold stuff too, and my memory isn't that great. I just check for residency requirements, and a conceal carry permit in some cases. After that, the person's name is inconsequential to me, so I really don't remember who they are or were.
Hopefully, I won't be required to scroll through pages of old forum posts to try to determine who the buyer was.
If forum's deleted all old conversations prior to these laws taking place, that would be horrible. How could we ever track these people down??????????????