RedScott

Well all rights end where they infringe on the rights of others. Or where they are dependent upon others for enactment. For instance you have the right to own a weapon, but you do not have the right TO a weapon. That is to say you are not entitled to a weapon in the sense that a European might say they have a "right" to medical care. (understanding that in that case while they may very call health care a "right" it is not at all such. It is a privilege.) So, to answer your question about "military grade weapons" I'd say yes, a person has an inherent natural right to own whatever type of weapon they see as necessary.

Now, one might make the claim that the founders could not foresee the type of weaponry that would be available to commoners in this day and age. I'm not altogether sure what one can pick up at a retailer, as I'm not a gun enthusiast myself, but I assume if one has the proper connections he could find his way to a pretty impressive weapon. Maybe a rocket launcher of some sort. Certainly a fairly heavy caliber machine gun. Would a strict and literal reading of the constitution mean it is impossible and illegal for governments to prevent these weapons from falling into citizens hands? Not at all, as A) there is an amendment process by which the government can legally petition the People to give them the authority to regulate these types of weapons and B) the US Constitution applies only the Federal government so the State governments can and should regulate their citizens weapons according to their own constitutions.

On the issue of preemptive strikes, like you, I believe Bush's logic for starting the war was garbage. Likewise any such preptive strike by an individual would be.