Actually they are.The words "common use" are not part of the 2A nor the Constitution.That it is up to the government to decide what is "common use" and that the founders meant that government should be better armed than the people contradicts everything ever written on gun rights by every founder who was involved in writing the Constitution
In US v. Miller, and as reaffirmed in Heller, whether or not a weapon is entitled to Constitutional protections is predicated on a determination of its being ‘in common use.’
The Constitution exists solely in the context of its case law, including the Second Amendment:
‘Miller said, as we have explained, that the sorts of weapons protected were those “in common use at the time.” 307 U. S., at 179. We think that limitation is fairly supported by the historical tradition of prohibiting the carrying of “dangerous and unusual weapons.”’