I think we get confused by the original intent of the Constitution. It was meant to create a strong central government that had certain express powers delegated to it.
At the time of its creation there was a debate between the Federalists, who wanted strong central government, and the anti-Federalists, who really feared it.
In one of the Federalist letters the Federalists argued
against creating a bill of rights. They feared that if they created one the people would eventually come to believe that they only had those rights specifically listed in the bill of rights when instead, the people were supposed to enjoy all rights that neither the Federal or state governments had been given power to interfere with.
Now we look at the Constitution and say "the individual has the right to keep and bear arms; it says so right here in the Second Amendment." And that's correct.
But more importantly, the power to prevent us from owning arms isn't specifically granted to either state or Federal government anywhere.
So yes, I believe they intended for us to own the same type of small arms that were in use by the military. Evidence of this - there were fusils and commercial muskets with bayonet lugs available at the time for anyone to buy, so you could obviously have a nearly identical weapon to what the individual line soldier was carrying. Furthermore, privateering wasn't unheard of - meaning that owning your own heavily armed ocean going ship wasn't unheard of either.
So I'd say that they at least expected civilians to have access to the same small arms, artillery pieces, and explosive devices commonly available to the military. One could even make an argument that attack aircraft, armored vehicles, and possibly even naval vessels should be covered.
Gouranga said:
you also reach a point though where you have to consider public safety. Imagine what a full auto M16 would do in a heavily populated area in the hands of an untrained fellow with enough money to buy one. In the stix is one thing cause you only endanger yourself and that IMO, is you right to do. The founding father did absolutely expect weaponry to advance, I wonder though if they would have even considered how far it would go. You would have a hard time accidentally loading a musket and an AD would result in a single shot not the potential of a full magazine of ammo being fired through a building.
A mistake loading a musket could result in a burst gun, which would be rather like a hand grenade and could injure or kill a lot of people. Additionally, imagine the consequences of getting too close to a fire with your powder horn. Black powder can be very unforgiving stuff - at least as much as a loaded M-16. To the best of my knowledge, there was not any training requirement involved in purchasing a musket or black powder. I actually think that people just accepted that there was a certain amount of inherent danger involved with living at that time. You could get gored by a bull and die of infection. You could get scalped by the Indians if something angered them sufficiently (and sometimes even if it didn't). Or the guy next to you could fail to seat the ball deep enough and his gun could burst, killing you. Or, as you charged your musket directly from the horn a spark could set off the pound of black powder in your hand, killing you and everyone around you. It was just how life was. I think the emphasis on "safety" is largely a modern thing that would have been foreign in many ways to the Founders.
With freedom comes risk. You can't have it both ways. IMO, based on my admittedly limited study of the American Revolution and its aftermath, I believe the Founders wanted the individual citizen to be able to arm himself as well as a regular soldier was armed - if he could afford it.