not quite Lazeelink....the 2nd Amendment refers to a "well regulated" militia, Chapter 13 refers to the 2 classes of militia in which all able-bodied males between 17 and 45 are classified as members, the organized militia encompassing the National Guard and the Naval Militia , and the "unorganized militia", who are all members of the militia not members of the Guard or the Naval militia.   

There is nothing in the 2nd amendment that magically de-links private ownership of firearms from association with membership in a well-regulated or organized militia in time of insurrection or external threat. You are correct...you are not compelled to join the  militia...but the private ownership of weapons was clearly to support their use within the bounds of membership in the militia under regulation in time of threat ...it has nothing to do with self defense from the neighbour or the right to carry a Glock into Wal-Mart