You know I've got an axe to grind on that, and I know that I'm against the position of the vocal minority on this.
There are two USSC decisions on that. The first,
US v Miller by a full court in 1939, holds that the 2nd amendment allowed congress's right to regulate a sawed off shotgun because the evidence did not show that the shotgun "has some reasonable relationship to the preservation or efficiency of a well regulated militia . . . .". This creates a collective rights theory of self defence. That was the continuing law in the US until
DC v Heller, in 2008, which concerned a ban on handguns and which was a 5 to 4 decision of the court with the five being the usual gang you'd expect them to be. Heller supported the individual rights theory of self defence.
I can't help but think that if the framers of the 2nd amendment were to see an interpretation permitting individuals to keep assault rifles in today's society they'd be spinning in their graves. Statutory interpretation means that every word in the legislation has to be given meaning. It's difficult to give meaning to "well regulated militia" in the Heller decision. It's not just that a "militia" is needed. It needs to be a "well regulated" one. And "well regulated" leads to collective defence and that leads to defence against outside threats and not the fictitious proposition that the frames of the constitution contemplated some future internal overthrow of the democratic republic that they had just created. The key elements to protect the citizens from the threat of the government becoming oppressive is the citizens' rights to elections of their government and a supreme court to evaluate laws.
To this point in time, 12 justices (8 in Miller, 4 in Heller) out of 17, support the collective rights theory. This parallels the public in general where
64% of the public in the US favours stricter gun controls. It is time that the US citizenry overthrow the tyranny of the minority that has unleashed the proliferation of uncontrolled firearms and insist that the term "well regulated militia" be given the meaning intended by the framers of the constitution.
$0.02