(For the image of a musket as I originally intended to go here, please see post just before this. Sorry)

The Second Amendment to the U. S. Constitution comes down to us from an age when rifles looked like the one pictured above. That is a late 18th Century musket, a muzzle-loaded flintlock action weapon that could fire 2-3 rounds per minute, depending upon the skill of the shooter.
Today’s mass killing weaponry, obviously, could not have been imagined by the Founders. To read the 2nd Amendment as a blanket, literal authorization to possess such things as assault rifles and large magazines is like reading the bible literally. It is, in effect, constitutional fundamentalism.
The most significant U.S. Supreme Court case authorizing possession of guns is District of Columbia vs. Heller, a 2008 decision involving a D.C. law banning possession of handguns in the home. [A more recent case, McDonald vs. Chicago (2010), upheld Heller and made clear that the 2nd Amendment was applicable to the states via the 14th Amendment.]
Heller, as often is the case in significant U.S.S.C. decisions, was decided by a close 5 to 4 vote. In his majority opinion, Justice Scalia wrote that the 2nd Amendment “protects an individual right to possess a firearm unconnected with service in a militia, and to use that arm for traditionally lawful purposes, such as self-defense within the home.” This effectively destroyed the argument that the 2nd A. as written should apply only to militia as envisioned back in the Framer’s day. No one had ever shot at Scalia’s children while they were in school, and he himself had always felt pretty secure in a movie theatre as the only guns going off were up on the screen.
But Scalia also opined that the right to keep arms has limits: “Like most rights, the Second A. right is not unlimited. It is not a right to keep and carry any weapon whatsoever in any manner whatsoever and for whatever purpose…” There is, then, a basis even in this gun right case to support restrictions upon assault rifles and large capacity magazines. The opinion states that it should not be read as casting doubt on “laws imposing conditions and qualifications on the commercial sale of arms.” He referred to an earlier Supreme Court case supporting “the historical tradition of prohibiting the carrying of dangerous and unusual weapons.”
As Justice Stephen Breyer asked in dissent: “Given the purposes for which the Founders enacted the 2nd Amendment, how should it be applied to modern-day circumstances that they could not have anticipated?” That’s the polarizing issue facing our violent, somewhat civilized country today.