The 9th Circuit had found the “Montana Firearms Freedom Act” was unconstitutional because it wrongfully tried to remove DC’s regulation of firearms from certain Montana-made weapons. The Act sought to create the concept of a Montana-only firearm which, according to the plain text of the Constitution, would be outside of the regulation of DC.
SCOTUS refused to hear the appeal from the 9th’s decision, thus making it the law of the land.
To state it another way: The US Supreme Court has agreed with the 9th that DC has no limits on its power.
Stop pretending the courts will save you.