I think the statement below is right on:
The original intent and purpose of the Second Amendment was to preserve and guarantee, not grant, the pre-existing right of individuals to keep and bear arms. Although the amendment emphasizes the need for a militia, membership in any militia, let alone a well-regulated one, was not intended to serve as a prerequisite for exercising the right to keep arms.
The Second Amendment preserves and guarantees an individual right for a collective purpose. That does not transform the right into a "collective right." The militia clause was a declaration of purpose, and preserving the people's right to keep and bear arms was the method the framers chose to, in-part, ensure the continuation of a well-regulated militia.
There is no contrary evidence from the writings of the Founding Fathers, early American legal commentators, or pre-twentieth century Supreme Court decisions, indicating that the Second Amendment was intended to apply solely to active militia members.