Being not American I'm not hugely familiar with the second amendment, so I'm grateful you out it down there in black and white.

My thoughts on that was that it was written in a very very different era. And in my view was written with the intent to protect the right to defend yourself with weapons against a tyrannical state or even foreign invader as you mentioned.

But I do feel it was written with the weapons of the time in mind. Muskets, single bolt action rifles. Not AR15s.

If you require, as a civilian, a weapon of that calibre, you sir are in way over your head. Although I believe you should be able to defend yourself against aggressors like tyrannical state. You're going up against a well funded and well trained military. No local militia is taking on the US army. You don't stand a chance. The best you could hope for is those highly trained persons side with you against the state. But don't delude yourself into a false sense of security that if the state wanted you gone, an AR15 or other military grade weapon isn't going to help you.

I don't mean to sound disrespectful with that last statement. But truly if you're fighting your own tyrannical govt. You're in over your head, find a way out, engaging isn't going to be a good or survivable option.