One interpretation of "keep and bear arms" might conclude that you would be limited to weapons that you can "bear"; i.e. carry. However, in the modern era, that would logically include Stingers, LAWS, and claymores.
If the primary intent of the 2am is to allow the citizenry to oppose the government, then "by rights" the citizens should possess arms comparable to those of the government. In colonial times, the militia was expected to arrive bearing their own weapons, but I don't believe that this included field artillery. A militiaman reported for duty with the same arms as any infantryman of the standing army. As I read history, in times of conflict, the government was intended to provide large arms, such as cannons and ships. There was no prohibition against citizens owning the same, it was just a matter of practical reality.
I'll skip the long explanation, but if I had to draw a line in the sand, Preacherman has picked a good spot to draw it. No crew-served or explosive weapons for civilian use.
BUT
I would include this proviso:
Civilian use mean ALL civilian use. NO agent (agency) of the government, outside of the military, would be allowed to use or possess any weapon that is not available to the general public. In other words, if the FBI gets a M4 shorty, I want one. If the ATF gets a silenced MP5, I want one. They are not the military.