According to the U.S. Supreme Court, it is unconstitutional to:
1) Charge a fee for the exercising of a right (Harper v Virginia Board of Elections 1966);
2) Require a precondition on the exercising of a right (Guinn v US 1915, Lane v Wilson 1939);
3) Require a license (government permission) to exercise a right (Murdock v PA 1943, Lovell v City of Griffin 1939, Freedman v MD 1965, Near v MN 1931,
Miranda v AZ 1966);
4) Delay the exercising of a right (Org. for a Better Austin v Keefe 1971);
5) Register (record in a government database) the exercising of a right ( Thomas v Collins 1945, Lamont v Postmaster General 1965, Haynes v US 1968).
When you compare these cases to most of the current gun laws throughout the country they are unconstitutional at best.