by this logic, shouldn't you be able to buy IEDs and RPGs (and launchers) at walmart? I understand these weren't available at the time of The War of American Independence, but going by the spirit of the Second Amendment, one would want people fighting tyranny to have the most effective weapons possible to do said fighting. Those(IEDs etc) seem to be the most effective weapons for a guerilla force fighting a tyrannical government (vs Glocks or whatever).
And if you are considering non guerilla forces facing off with government forces, you probably need artillery and heavy machine guns (to start with).