The scope of the Second Amendment is clear:
It's no narrower than the First Amendment.
Since the 14th Amendment incorporated the First Amendment to the state and local governments, so to did it incorporate the Second Amendment.
Not only that, the First Amendment states that "Congress shall make no law" abridging freedom of speech, etc. The Second Amendment merely states "the right to keep and bear arms shall not be infringed", without reference to the identity of the infringing agency.
The court has already ruled that the right to keep and bear arms is an individual right. (there are no "collective" rights, ie, rights held by a group that cannot be held by an individual in the group).
So I fully expect the four Rodents, (Kagan, Sotomayor, Brayer and Roberts) to rule against the Second Amendment, and hopefully the other five will do the right thing.