The second Amendment should not be interpreted as an unconstrained individual right. It was intended to avoid a standing national army, which might then pose a threat to a central government. History demonstrates that military coups generally bring an end to governments.

“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.”

The civilian population of the states, not appointed or trained by the federal government but regulated in a militia, were granted the right to keep and bear arms, as opposed to a more conventional standing national army. Naturally there would have been anticipation by those considering the ratification of a national constitution, that a standing army would eventually be established and render state mustered forces unwarranted, hence the placating “shall” statement.

In the Militia Clauses (U.S. Const. art. I, § 8, cls. 15–16). Under the Constitution, the militia is to be available for federal service for three distinct purposes: "to execute the Laws of the Union, suppress Insurrections and repel Invasions." Congress is to organize and discipline the militia, and the states are to appoint officers and train the soldiers.