There is an interesting discussion of the second amendment at the Atheist Experience blog here:
http://freethoughtblogs.com/axp/2012/12/12/answering-justice-scalia/
It starts out on a different topic, but addresses the 2nd starting at post #26. I think the point is fairly made that the intent of the founders was that the militias - however, and by whomever, organized - were comprised of an independently armed citizenry. Their purpose was not to act at the behest of the government, but to be available to overthrow it it if monarchic or despotic tendencies arose.
Capt.