One can learn a great deal from filings of this nature:
Especially telling are these Amicus Brief filings:
In Support of Respondents
You can crack these babies open and find out who DOES NOT support gun rights...

And this really has more than just the 2nd Amendment as its foundation:
Whether the Fourteenth Amendment prohibits state and local governments from exercising their police powers to prohibit the possession of handguns based on a judgment that these firearms are unreasonably likely to be misused by criminals.