The U.S. Supreme Court in District of Columbia v. Heller (2008):
Some have made the argument, bordering on the frivolous, that only those arms in existence in the 18th century are protected by the Second Amendment. We do not interpret constitutional rights that way. Just as the First Amendment protects modern forms of communications, e.g.. Reno v. American Civil Liberties Union, 521 U.S. 844 (1997), and the Fourth Amendment applies to modern forms of search, e.g., Kyllo v. United States, 533 U.S. 27,35–36 (2001), the Second Amendment extends, prima facie, to all instruments that constitute bearable arms, even those that were not in existence at the time of the founding.
And yet the Court also said this in the same decision:
We therefore read Miller to say only that the Second Amendment does not protect those weapons not typically possessed by law-abiding citizens for lawful purposes, such as short-barreled shotguns. That accords with the historical understanding of the scope of the right, see Part III, infra.
But doesn’t this, as the Court suggests later in the opinion, limit “the degree of fit between the prefatory clause and the protected right”? And more importantly, isn’t the right to bear arms about something broader than merely being prepared for militia service and able to perform self-defense defined as protection of the home and self from other citizens?