Your statement falls back on Barron v. Baltimore, which in 1833 decided that the bill of rights applies only to the federal government. This decision was so wrong it is difficult to understand how it was made. Article VI of the constitution is clear: "This Constitution, and the Laws of the United States which shall be made in Pursuance thereof; and all Treaties made, or which shall be made, under the Authority of the United States, shall be the supreme Law of the Land; and the Judges in every State shall be bound thereby, any Thing in the Constitution or Laws of any State to the Contrary notwithstanding."
The fact that the Supreme Court ignored this is more indicative of the politics of the day and a convenient situation for all in power - you do your thing and we'll do ours. The Supreme Court has screwed up plenty of decisions, we can go from Roe v. Wade through Dred Scott and all the way back to Marbury v. Madison for examples of the court inventing things that defy the constitution.
In a state? No. I don't think the thought ever occurred to them.
"Your statement falls back on Barron v. Baltimore, which in 1833 decided that the bill of rights applies only to the federal government."
I think that was the first case, yes. The court only referenced the Takings Clause of the 5th amendment, not the entire BOR.
"Article VI of the constitution is clear"
Uh-huh. And for the next 150 years, every single court ignored it? C'mon. Read the Preamble to the Bill of Rights. It says right in it that the amendments are to apply to the federal government only.
Well, any part of the Bill of Rights that speaks of "Congress shall make no law" clearly is not refering to the States. After all, some States had various established religions in place for many years after 1789. Fortunately for this argument, the 2nd Amendment is not phrased that way.
More convincingly, the 10th Amendment would seem to make clear that regulating the ownership of arms, being protected by the 2nd Amendment, is therefore both (1) not a power delegated to the United States, and (2) is a power prohibited by the 2nd Amendment to the States.