Clarification.
I hate legalese, and legal reasoning. Let me try again.
In my opinion, there is nothing in the Constitution or the Bill of Rights that can be construed to say you can't own a firearm.
But neither is there anything there that can be used to prevent a state from passing a law restricting gun ownership. In my opinion, that would require a constitutional amendment.
Of course, that's all academic now. The law is whatever the Supreme Court says it is.