Thanks Ardy. It does seem that some sort of obligation is being asked of the citizens for the granted right to bear arms. But the Militia Act of 1903 created the National Guard thereby eliminating the need for state militias. So now we have the right to own guns with no obligation to be on call to serve in a state militia. What would a replacement obligation be?
Many say citizens need to be armed to protect against tyranny of an overbearing federal government. I find this argument a little disingenuous. I think the real reason is that for most, they like to hunt, they feel protected from other people by possessing a firearm, and just like to shoot their guns for fun. There is nothing wrong with that as long as their guns are not being aimed at other innocent human beings, and for that we have laws.
As far as stopping potential government tyranny—come on—imagine sitting at home with your choice of rifles and handguns and coming up the street is an Army M1A1 Abrams tank supported by Blackhawk helicopters and an Air Force AC-130H/U Gunship. Are you really going to stop that with your tiny arsenal?
But have no fear gun lovers. In this day of instant communications and the internet, any attempt at disarming the American public would be a fools errand at best IMHO.