Can anyone stand up and defend a clip that carries 100 rounds? The only reason I can think of for anyone would want one is to kill large amounts of people. So why are these things sold?

The BASIC reason for the Second Amendment is not home or personal protection, or sport. Though both of those are important, at least to some of us, it's quite true that neither reasonably requires a weapon with a hundred-round magazine.

The real reason for the Second Amendment is that the citizens be prepared for the time when the President declares a national emergency for whatever reason, and announces that he is suspending the constitution "for the duration," and placing the Justices of the Supreme Court, and the leaders of both parties - or at least of the Democrats - in Congress and the Senate, in protective custody. Or, alternatively, when the Joint Chiefs of Staff make the declaration, and place the President in protective custody also. Since the Constitution contains no provision for its own suspension, such a declaration would make the maker or makers thereof outlaws on the face of it, and oblige all citizens who have sworn to uphold the Constitution to take up arms forthwith. So it's necessary that they have sufficient arms to take up.

There are two standard objections to the above concept. The first is that such a thing could never happen in the US. I would simply ask how many countries in the world it HAS happened in. And it would not be a new thing for Americans to find themselves fighting Americans. And if you still don't think it's possible, two words: Dick Cheney.

The other objection is that citizens with small arms would stand no chance against the professional military, with heavy weapons. There's something to that - but they'd have more chance than with no weapons at all. And the military themselves would probably split down the middle, between those members thereof who knew something about the Constitution, and respected their oath to uphold it; and those who only understood Obedience. Also, heavy weapons are not much use in street fighting within towns or cities, unless you're willing to destroy the city to get the enemy. Which makes very little sense if you want to control the city yourself.

So, as an outsider in the Liberal/Conservative wars, it's always seemed odd to me that the liberals were the ones who were so anti-gun. They have the most to lose by suppression of the Second Amendment. Remember Robert Heinlein's Future History, promulgated in the 1940s. He had 2012 being the last national election, as a Christian fundamentalist candidate would get elected President and have a fundamentalist dictatorship established by 2016.

I submit that "unarmed free citizen" is an oxymoron.

P.