The original Federalists argued against the adoption of the Bill of Rights on the grounds that it was unnecessary. It turns out that it didn’t really matter whether they or the Anti-Federalists won–our political cancer is so far advanced that the modern left and its judicial activist corps will creatively read anything into or out of the Constitution they please.
But as a legal matter, the Federalists were surely correct. The U.S. federal government has certain specific enumerated powers. The power to, say, ban AR-15s is not, and never was, one of them. Therefore the Feds cannot legally, justly, morally, or constitutionally do it, whether the Second Amendment exists or not.