The government may attack a few fringe groups without serious problems. But trying to take the guns of the population at large has been tried before. It started the most important war in US history.
http://www.davekopel.org/2A/LawRev/american-revolution-against-british-gun-control.html
Are Americans a different species than the people in those countries? Do we really have some magical genetic protection from it ever happening here?