Citizens have a right and, arguably, a duty to own the weapons and equipment of a light infantryman, including crew served weapons, anti-tank weapons, etc.
And to also include the equipment necessary to outfit personally owned seagoing vessels and coasters as Privateers, should congress chuse to exercise its authority to issue Letters of Marque and Reprisal.
As, for example, chartering a Blackwater/Xe, OMTA or Cohort operation against terrorists or Somali pirates.
"Happiness is a belt-fed weapon." :-)
Actually, if you recall the precise wording of the usually-disregarded first clause of the Second Amendment, it's something a bit more than a right or duty:
As ratified by the States and authenticated by Thomas Jefferson, then-Secretary of State:
A well regulated militia being necessary to the security of a free state, the right of the people to keep and bear arms shall not be infringed.
Since those citizens bearing arms [the militia] are deemed necessary to the security of the free state, it follows that their duties must include dealing with those who would dismantle or attack that state from within, giving aid and comfort to, and adhering to our enemies. In the time of the founders and constitutional authors, that would have included Tories who had supported the English cause [aka *loyalists*; loyal to the British King] and hostile/enemy Indians, as tribes, renegade groups or individuals. And even in Jefferson's day, there were difficulties with islumist nations and pirates.
Indeed, one essay at the Constitution Society suggests revitalizing the Militia for just such a purpose.