"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
This means the right to state militias, and, more broadly, the allowance of regular citizens to own guns. It does not mean that things like bans on assault rifles are somehow illegal.
Granted, my knowledge of the US Constitution is minimal but doesn’t the old-timey phrase “A well regulated Militia, being necessary to the security of a free State” translate to “A well run military, is necessary to the security of a free country”. Who would disagree with that? (except dictators and the British monarchy of the day).
Does it say somewhere else that “free state” specifically means “the right to state militias” and not as it reads?