Simon,
If you want an honest debate about this you should do some research on what the framers of the Constitution meant by "militia." Its at least as relevant as what they meant by "firearms."
And to answer your question, we have accepted some reasonable limitations on the right to bear arms for quite some time. Military grade weapons, such as fully automatic rifles and machine guns are highly regulated, and I've never seen a weapon that fires explosive shells for sale to private citizens.
There may be some nuts around advocating a right to own tanks or whatever, few serious people take such a position. Asserting an argument from an absurd position is what's inane.