Sources? I don't believe this interpretation is correct. I will take the originalist / original intent approach for the purpose of this debate (in other words, I'm assuming the role of devil's advocate; I actually don't resort to original intent often). Second Amendment scholar Dr. Chris Bogus wrote in 1997, for the University of California at Davis Law Review, on the original intent concerning that amendment——and he surveyed the history surrounding the meaning of "militia"——in his article "the Hidden History of the Second Amendment." "Well-regulated" does not simply mean "good working order;" Professor Bogus wrote of statutes in Georgia in 1755 and 1757 which mandated that plantation owners perform regular patrols to keep slaves in check; these bodies were regulated by the state, which appointed commissioned officers. The purpose of these patrols, as will be seen, were to defend plantations against uprisings; and, as will be seen, the drafting and subsequent ratification of the second amendment had nothing to do with tyranny per se.
Its drafter, it appears, inserted the clause to appease one state in particular——Virginia. These militias were designed to mitigate and prevent slave insurrection / uprising, which was a vivid fear among plantation owners. These owners were a minority by well-accepted numbers, in Virginia and in parts of other slave states. Virginia, much like other southern states, feared that a federalism would infringe on their ability to maintain these slave-taming militias, and that a central authority would disarm them as part of some abolitionist aspiration.
Virginia's approval, as the drafters observed, was instrumental to ratification, and absent its approval, the union would have failed to materialize at the time that it did. Virginia was the locus of the Antifederalism pulse——in particular, Virginian politician and lawyer Patrick Henry, who apparently conceived of the "states' right" expression——, and much of the fear of scaled-back states' rights came from Virginia and its southern neighbors. Federalist James Madison, then, in order to appease Antifederalists like Patrick Henry and his constituents, drafted the Second Amendment and inserted the dependent clause "a well-regulated militia, being necessary to the security of a free State, [...]" (Notice, as I have emphasized, the word "state;" this is further evidence that this very much had to do with states' rights as Professor Bogus argued).
In opening line of his examination of the Second Amendment, Professor Bogus wrote:
"This Article challenges the insurrectionist model [the insurrectionist model = the purpose of the 2nd Amendment is for armed citizens to fight tyranny]. The Second Amendment was not enacted to provide a check on government tyranny; rather, it was written to assure the Southern states that Congress would not undermine the slave system by using its newly acquired constitutional authority over the militia to disarm the state militia and thereby destroy the South's principal instrument of slave control. In effect, the Second Amendment supplemented the slavery compromise made at the Constitutional Convention in Philadelphia and obliquely codified in other constitutional provisions."
As I inserted in brackets, the insurrectionist model has been around for quite some time; many have argued, and repeated, that the purpose of the amendment was to empower and arm citizens against a government that has become tyrannical, thereby implanting the seeds of a revolution——without an armed body, they argue, an uprising against tyranny is impossible. As Dr. Bogus tried to articulate in his piece, that was not the original intent of its drafter and ratifiers.
