If the 2nd amendment were still in force, there would be not a single federal weapons law and it would be entirely a matter for state or local jurisdiction. The BATF should not exist.
If the Second Amendment were in force, states would also be prohibited from violating this right. The Second Amendment explicitly states that this right belongs to the people, not to the state nor the federal government, and explicitly forbids this right from being infringed. Period.
See also, the Tenth Amendment, which speaks of powers (rights) belonging to the federal government, to the states,and to the people. The primary point is that the federal government has no authority to usurp powers belonging to the states or the people; but it follows, even though not explicitly stated, that the states likewise have no authority to usurp powers (or rights) that belong to the people. And the Second Amendment explicitly identifies the right to keep and bear arms as belonging to the people.