That might be a justifiable reaction if the item in question were a shotgun or a rifle (or even a handgun), but assault rifles have one purpose: killing people.
That's incorrect. The purpose of an assault rifle is to propel metallic projectiles at thousands of feet per second, at a rate of dozens of projectiles a second; as opposed to handguns, which, while also proppelling metallic projectiles thousands of feet per second, do so at a rate much slower. An assault rifle, in my possession, would have the same purpose - I, however, would have the purpose of protecting myself not only from criminal elements, but from an oppressive government who, if it is already assuming the exclusive right to automatic weapons, will shortly begin assuming other rights (the right to ban gay marriage? the right to ban stem cell research? the right to taxation without representation? the right to unreasonable search and seizure?). With the recent Bush-signed legislation regarding terror-suspects, habeas corpus can now be legally withheld, for the first time in American
history. Anyone - American citizens included, can be detained, interrogated, tormented unto confession, and have that confession used to jail them indefinitely, so long as they are applied a label of "enemy combatant." You think this is a joke, son? The slippery slope argument ain't so funny when you're sliding towards the Fourth Reich.
Also, how would banning assault rifles be spitting in T. Jefferson's face (aside from the second amendment, which I don't think counts)?
Thomas Jefferson is well known for his vehement defense of the right of the people to arm themselves. He would roll over in his grave right now.
*edit - for those not in the know, habeas corpus is the right to be tried in court, for your charges to be made known to you and the people, and your right to defend yourself from the charges. The last person I know of to try and suspend habeas corpus was Lincoln, in the Civl War - and even then his attempt was shot down by the Supreme Court. But as another founder, James Madison said, "If tyranny and oppression come to this land, it will be in the guise of fighting a foreign enemy."