Within the collective vs. individual right debate is the issue of just what constitutes a militia. If one relies upon "originalism" then the definition of a militia during the founder's era would provide a useful insight.

Suggested resource to investigate that question = The Militia Act of 1792 to be found at "A Century of Lawmaking for the New Nation: U.S. Congressional Documents & Debates 1774 - 1875 ----Statutes at Large, 2nd Congress, 1st Session (Ch. 33) "every citizen so enrolled . . . provide himself with a good musket or firelock, a sufficient bayonet, . . . ."