A fully-automatic AR-16, the military equivalent of the gun James Holmes used in Colorado, is capable of firing 800 rounds per minute. That's roughly 13 bullets per second.
Holmes' AR-15 was semi-automatic, which means it could fire bullets as fast as he could pull the trigger. That's about 200 rounds per minute.
You cannot legally own a fully automatic rifle, basically a machine gun, in this country except under very special circumstances. But why not? What's the difference between being shot by three bullets per second versus thirteen bullets per second? You're just as dead.
My point here is that if we can write laws that limit guns to a certain rate of fire, which we clearly already have, then why not simply limit guns to, say, one bullet per minute? This would be similar to the rate of fire of a flintlock rifle, the standard weapon when the Amendments to the Constitution were written. At the very least we could limit all guns to one bullet at a time, no magazines or banana clips. A one-shooter.
You may think this is a dumb idea, but what is really dumb is allowing anyone and everyone easy access to weapons that fire 200 rounds per minute.