Unfortunately, on the right to bear arms, the founders did not say what they meant, and did not mean what they said.
A Little History
The Second Amendment has produced cognitive dissonance and a lack of candor regarding the relationship between liberty and arms. The resulting confusion has enabled us to indulge in a deadly mix of immature fantasy and apodictic certainty, disconnecting us from reality to a degree that we can no longer, putting it mildly, afford. A more grownup and realistic confrontation with the process that gave us our constitutional rights--bitter medicine, perhaps--might be a precondition to curing what seems to ail us so desperately.
The realpolitik in which the Second Amendment was framed, during the first U.S. Congress of 1789, involves some unedifying but illuminating features. The amendment was a response to the federal government's power over state and local militias, as set out in Article I, Section 8, of the Constitution. That provision had been among the most hard-fought at the Constitutional Convention of 1787. Delegates committed to state sovereignty feared--rightly enough--that if the federal government were empowered to control the state militias, states would lose sovereignty.
In that elemental debate lay the beginning of a perennial American disingenuousness regarding arms and rights. Delegates led by James Madison wanted to create a national government, directly acting on and protecting all citizens, throughout all states. To achieve it, they had to play down how entirely they wanted it, how nearly utter the states' loss of power would be. Madison's convention notes show Madison himself, along with other nationalists, minimizing the impact of the federal militia power in order to soothe certain delegates' fears of losing state sovereignty.
As we know, the nationalists got what they wanted. Despite concessions to their opponents' ideas about state sovereignty, we became a nation. And critical to that achievement was the constitutional provision giving the federal government control of states' military institutions.
So when amending the Constitution, Madison continued to prevaricate. Former antifederalists in Congress and the state legislatures still resented the federal power to control militias; they were hoping to use the amendment process to regain some military control and thus retain some sovereignty. In the Second Amendment, Madison tried to defeat those hopes by placating them without really addressing them. The amendment gestures vaguely at state sovereignty in a way intended to make little practical sense.