So Hop, what exactly do you think the purpose of the 2A is, if not security from a tyranical government? While many of our laws have their roots in english common law, those English common laws now have no bearing in our system. If it was truly derived from english common law, I think justice Sotomayor would like it a lot more. Our laws are our own, pulled together from the best of the rest.
The writtings of our founders tell us about what they intended in writting the laws and constitution. The way I interpret their writtings is that the 2A was for the security of a free state. Secure against domestic individuals, natural dangers, and governmental dangers, foreign and domestic. It is the best way of ensuring that the power stays with the people, and the people take responsibility for thier own security.