What they were really doing, as explained in the preamble to the Bill of Rights, was preventing government from using any of the powers it was granted in the original body of the Constitution in ways not amicable to the rights of the people. That preamble is given below:
The conventions of a number of the States having at the time of their adopting the Constitution, expressed a desire, in order to prevent misconstruction or abuse of its powers, that further declaratory and restrictive clauses should be added.
You missed the word “misconstruction”, to wit: we didn’t mean for the feds to have a certain power, but someone managed to concoct it out of the Constitution’s wording anyway.
Nothing in the Constitution was intended to give the feds any power to disarm the people (or prohibit any inanimate objects), but eventually the political desire to do so deliberately misconstrued the “commerce clause”, along with the general power to legislate, into rationalizing that power into existence.