I called in to a local AM radio show Monday afternoon and was met with this exact question. My reply went something like this:
The founder's view and opinion of 'Arms' at the time of the revolution included everything from cannon's down to knives. Our own navy started with civilian owned merchant ships armed with civilian owned cannons mounted on them.
Now, in our own time, I would expect the founders to be completely comfortable with the type of arms used by our war fighters in the sandbox at the platoon level. The 2A was written for self defense and to be able to resist tyranny. Platoon level weapons are certainly within the scope needed to resist tyranny.
The radio host found that to be a good answer and measure.
We have lawyers and guns." -- Gene Hoffman