The Occasional Observer

From page 11, refuting that the right is limited to 18th century weaponry:

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, 849 (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.

From page 30, on why the right is not tied to membership in the/a militia:

If, as they [the District of Columbia] believe, the Second Amendment
right is no more than the right to keep and use weapons as a member of an organized militia, see Brief for Petititioners 8—if, that is, the organized militia is the sole institutional beneficiary of the Second Amendment’s guarantee—it does not assure the existence of a “citizens’ militia” as a safeguard against tyranny. For Congress retains plenary authority to organize the militia, which must include the authority to say who will belong to the organized force...

Thus, if petitioners [the District of Columbia] are correct, the Second Amendment protects citizens’ right to use a gun in an organization from which Congress has plenary authority to exclude them. It guarantees a select militia of the sort the Stuart kings found useful, but not the people’s militia that was the concern of the founding generation.