>My understanding is that it is the SC that determines what the
>Constitution says, and it has made no ruling on the meaning of
>the 2nd.
Your understanding is faulty then. The second amendment is by now probably carved in stone somewhere. The SC simply provides interpretations. As with the "word of god" and other authorities, the interpretations will continue to vary, but the words will remain the same.
When read in the context of the rest of the amendments the second becomes clear.
Martin