Maybe you should research Haynes v US which concluded that the only people required to register guns were law abiding. Criminals cannot be tried for failure to register because that would be self incriminating. What is boils down to is that only law abiding people are hindered under gun laws - not criminals.

Of course that wouldn't bother a leftist like yourself who doesn't care about rights or freedom of individuals.

The Printz case has only to do with what the fed can and cannot require a chief law enforcement officer to do. In this case, the fed cannot require a cleo to do a background check on anyone.