The question has been asked a few times in this thread, but I haven't seen it answered yet. I think that while your interpretation of the 2nd Amendment, as it was originally intended, is correct, it does not speak for the current times and needs itself to be amended.
We do not have state militias capable of defending against an invading army. I'm not saying the common citizenry couldn't be roused quickly to offer a respectable defense, but the weapons used nowadays by armies are not accessible by the common man, nor should they be. Perhaps you disagree with that last statement, but then I would ask you, do you actually think that the general public should have unfettered access to the kinds of weapons needed to fend off any army? I would argue that the technology has changed to the extent that giving everyone any weapons they can afford creates a situation where come people will be driving tanks to work and gangs will have rocket launchers.
The original framers were good, reasonable men, but they weren't fortune tellers. I think you're fighting for the wrong thing.
By your logic, people should be allowed to own nuclear weapons!