Like most rights, the Second Amendment right is not unlimited. It is not a right to keep and carry any weapon whatsoever in any manner whatsoever and for whatever purpose: For example, concealed weapons prohibitions have been upheld under the Amendment or state analogues. The Court’s opinion should not be taken to cast doubt on longstanding prohibitions on the possession of firearms by felons and the mentally ill, or laws forbidding the carrying of firearms in sensitive places such as schools and government buildings, or laws imposing conditions and qualifications on the commercial sale of arms. Miller’s holding that the sorts of weapons protected are those “in common use at the time” finds support in the historical tradition of prohibiting the carrying of dangerous and unusual weapons.
Lower courts and liberal governments have taken this to mean that anything they wish to ban is OK, and until the Supreme Court takes on another 2A case, the district courts will uphold any scheme to ban guns and magazines that the states choose to dream up.
“prohibiting the carrying of dangerous and unusual weapons.”
Regarding this wording in Heller, the only weapons I can think of that should fit this category are biological and nuke type weapons, since their power can’t be controlled and they would indiscriminately kill tens of thousands of innocents. Of course Heller doesn’t clarify that statement, but any weapon that can be controlled by the owner should be Constitutionally protected. Guns with large magazine capacity certainly fit that category.