We have the Constitutionally protected right to keep and bear arms, not to keep and bear only certain specific weapons. Just like we have the protected right to freedom of the press, not freedom to print something on only a movable type hand powered printing press.
Too often this discussion gets parsed into the mind-frame of "do you NEED such and such weapon"; or "Why do you need such-n-such", when the real weight should be in the opposite direction. Because our Constitution declares that the citizens have the Right to keep and bear arms, and forbids the government to infringe upon that inherent Right, if the state desires to do so, it must have an overwhelmingly compelling, and specific, argument to be able to do so. There is no overwhelmingly compelling argument for banning ALL the US citizens from owning any of those specified weapons. Frankly I don't think that most of the existing gun ownership laws (and many other of our laws in fact)are within the intention of the Constitution.
As I've said before I agree that there are some common sense limitations that could exist. However, the attempted method of implementing them is horribly flawed. We can not let Congress pass laws the limit one of our Constitutionally protected Rights, because it seemed like a good idea at the time. By doing so we are opening the door for them to limit ANY of those other protected rights. IF someone feels that one of those Rights should be reduced in scope, then they need to make a much better argument, and get an amendment to our Constitution passed, not just pass an ordinary law.
We let it happen in the 30s from the fear of the mafia when the federal government virtually banned the real assault (fully automatic) weapons. In order to own one you must pay for an expensive federal license (as well as other heavy restrictions). If owning property, or paying a poll tax, infringes on a citizens Constitutional right to vote in an election, then an expensive federal license does the same thing to keeping an bearing arms.
i completely agree that the state does not have a case for banning assault weapons, since they are used in very few crimes or mass shootings, recent cases notwithstanding. therefore, if we are only going to ban weapons that the state has a severe interest in controlling, we should ban all handguns and pistols, since they are used in 90% of all crime and murders by firearms. but of course, the supreme court just upheld the right of individuals to own handguns in the Heller case. however, they left the door wide open on the government's ability to regulate and control the use and ownership of those weapons. once again, the 2nd amendment has a lot of room for regulation, and specifically says so in the first sentence. simply because you see it as an absolute right does not make it so.
edited to add: congress can and does pass limits to our constitutional rights all the time. you have clearly defined limits of free speech and religion, and there are many cases of 1st, 4th and 5th amendment rights being limited by the passage of laws and other means. don't pretend that the entirety of the Bill of Rights is somehow sacrosanct just because you don't want any limitations on the 2nd amendment.
"That's the trouble with political jokes in this country... they get elected!" -- Dave Lippman