Those are dealer sales only via FFL. No records of sale or transfer is
required by most states, as far as I know. MA seems to be one of the
few that maintains a record of private transfers, but it's almost
voluntary. You are supposed to report it on-line but there's no way of
determining if everyone does. However, if ever used in a crime and
found, it would be traced back to the original purchaser (via FFL)
unless transfers *have* been reported as required. That is the
motivation to comply.
The good guys will comply with whatever laws exist.
If only they could find a way to track guns in the possession of the bad
guys who really don't want you to know?
Round and round we go. How do the "bad guys" get guns that can't be
traced? From "good" guys, initially. Unless of course they have basic
machine shop skills and can whip one up on a lathe. :-) I don't think
I'd volunteer to be first in line to fire one of those though. Even
major manufacturers have had problems: