A well regulated militia, being necessary to the security of a free state

Well, most free states seem to get by without having one.

That would seem to imply that the meaning of this clause has to be recognised as conditional - ie "In circumstances where a well regulated militia is necessary to the security of a free state the right of the people to keep and bear arms, shall not be infringed."

So if circumstances are not such as to require such a militia - what could be called normal circumstances - this would no longer apply.