The essential argument of the crusaders for no controls on guns is that if the citizens can't have all the weapons they want, then they will be defenseless against a tyrannical government.
I believe that the reality is these crusaders are driven by the urge to intimidate peaceable citizens, and to overcome democracy with violence and threat of violence.
To me the historical event that best illuminates the roots of the gun fanatics is the Wilmington Insurrection. Using guns and other violence, white supremacists deposed the elected city government of Wilmington, North Carolina. They murdered and terrorized many blacks, burned down the building that housed the newspaper operated by blacks, drove black citizens out of town to turn it from majority black into a majority white town, and subsequently worked hard at voter suppression to keep it that way. Here is one website about these events in our history: http://www.pbs.org/... . Until Michigan's new laws effectively took away the rights of voters to elect their own local governments, this was the only coup d'état in our history, I think.
The real meaning, as I see it, behind the rhetoric of preserving our liberty by defending against tyrants, is the ongoing momentum of the confederacy.
If the gun advocates really wanted to overthrow a government they considered tyrranical, computers would be much more important to their efforts than hunting rifles. Communications and logistics would be essential, as would be cyber attacks on government sites. Really, they are talking about terrorism and anything that would involve, like getting their hands on WMD. You can't overthrow a modern government with a .22 or a six-shooter.
Their interpretation of the constitution is aimed at enabling a small minority of violence-minded "patriots" to intimidate everyone else into submission.
By the logic of those who romanticize uncontrolled gun ownership as a road to freedom, the second amendment protects a right of all citizens to have (and deploy) any weapon of mass destruction.
The success of the insurrection at Wilmington is a model for the way guns could be used by those who interpret the second amendment this way.