A quick thought on the Second Amendment
Seems to me that the spirit behind the Second Amendment is one of keeping the citizenry in a position to take down an out-of-control government.
In 1791, the best known way to do this was via a well-regulated militia. Not any more. A completely out-of-control government would today have access to satellite-guided cruise missiles and nuclear-armed stealth bombers. Occasional small arms fire against infantry or law enforcement officers would accomplish nothing.
Today, the only way to keep with the spirit of the Second Amendment would be to give the citizenry well-regulated tools to throw out a government before it goes completely out of control. Today, well-regulated whistle-blowing and leaking of classified information would damage a misbehaving modern government more than a well-regulated militia would. So would a well-regulated way to strike and protest in a way that significantly disrupts economic activity (by blocking all entrances to a major port, say). So would well-regulated avenues to organise and communicate anonymously. In 1791, none of these would have possibly worked.
200 years from now, taking down an out-of-control government would likely require still-different tools. Defending the Second Amendment therefore, is likely better done for its spirit rather than its letter. Its spirit can only ever match its letter if a well-regulated militia is about as well-trained and well-armed as the best of government forces. No one thinks of advocating for the private ownership of helicopter gunships and rocket artillery, however. So we should stop obsessing about guns and start looking for well-regulated ways that, in an extreme emergency, would allow for a grass-roots bringing of an abusive government to its knees.