David Dow has done a better job than I would of explaining a “well regulated militia”
Be sure to watch the YouTube video by Bill Whittle that he links at the end.
Mr. Whittle made an even better 2A speech as part of his “virtual president” series.
I just noticed that I already wrote a short piece about the meaning of well-regulated.
Some people apparently believe that “well-regulated” has a significantly different meaning than “well regulated”. The latter is in the actual text of the Second Amendment. The former is often written instead by people quoting it (and they often omit a comma or two). I don’t know.