The only interpretation that would make sense at all would be
taking the first two parts as an absolute construction, and the
the other two as the main clause. With modern punctuation, it
would look like this: A well regulated Militia being necessary
to the security of a free State, the right of the people to keep
and bear Arms shall not be infringed. The part in italics is an
absolute construction, as it is still used in modern English, to
be paraphrased as because a well regulated militia is necessary
to the security of a free state...; the main clause speaks for
itself. It seems some modern-day politicians have committed the
error of interpreting this sentence in an unhistorical manner:
the use of commas has changed quite a bit since the time this
sentence was written, and it should be read according to the
punctuation conventions of that time. The use of commas wasn't
as well established in 1791 as it is now: the connection between
pause and comma was much stronger (commas now mark about 50 %
pause and 50