Among the post-Newtown gun law reforms being discussed is a limit on the number of bullets that magazines can hold. Sometimes opponents of such reforms invoke the Second Amendment's guarantee of a right to bear arms. That strikes me as a stretch, given that the Second Amendment was conceived in a time when there was no such thing as a gun that could shoot more than one bullet without reloading. I mean, if the Amendment applies to weapons that didn't exist when it was written, why shouldn't it apply to machine guns, or grenade launchers, or even shoulder-fired anti-aircraft missiles? I recently raised that question with someone who opposes limits on magazine size -- Jacob Sullum of Reason Magazine, who has thought and written a lot about this stuff. And it turns out he does think machine guns are constitutionally protected. As for grenade launchers and shoulder-fired missiles -- he's less certain about those. Here's the exchange:

You can see the continuation of this conversation here, and you can watch the whole conversation from the beginning here.

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