Heres more dealing exactly with what your saying.
It may be objected that if weapons that are most useful
in military service—M-16 rifles and the like—may be
banned, then the Second Amendment right is completely
detached from the prefatory clause. But as we have said,
the conception of the militia at the time of the Second
Amendment’s ratification was the body of all citizens
capable of military service, who would bring the sorts of
lawful weapons that they possessed at home to militia
duty. It may well be true today that a militia, to be as
effective as militias in the 18th century, would require
sophisticated arms that are highly unusual in society at
large. Indeed, it may be true that no amount of small
arms could be useful against modern-day bombers and
tanks. But the fact that modern developments have limited
the degree of fit between the prefatory clause and the
protected right cannot change our interpretation of the
right.
It may be objected that if weapons that are most useful
in military service—M-16 rifles and the like—may be
banned, then the Second Amendment right is completely
detached from the prefatory clause. But as we have said,
the conception of the militia at the time of the Second
Amendment’s ratification was the body of all citizens
capable of military service, who would bring the sorts of
lawful weapons that they possessed at home to militia
duty. It may well be true today that a militia, to be as
effective as militias in the 18th century, would require
sophisticated arms that are highly unusual in society at
large. Indeed, it may be true that no amount of small
arms could be useful against modern-day bombers and
tanks. But the fact that modern developments have limited
the degree of fit between the prefatory clause and the
protected right cannot change our interpretation of the
right.