To protect the basic rights of Americans--rights which each person possesses and that are guaranteed, but not granted, by any government--the framers added the first ten amendments to the Constitution as a package.
Those amendments have come to be known as the Bill of Rights.
In constructing the Bill of Rights, Madison followed the recommendations of the state ratifying conventions.
Though they ratified the Constitution, several of those conventions had recommended adding provisions about specific rights.
The Constitution, and particularly the Bill of Rights, was created to specifically describe the powers of government and the rights of individuals government was not allowed to infringe.
Some people claim that there is no individual right to own firearms.
The amendments he wrote would not change anything in the original Constitution.
Madison repeatedly insisted that nothing in the original Constitution empowered the federal government to infringe on the rights of the people, specifically including the right of individuals to have guns.
To understand the true meaning of the Second Amendment, it is important to understand the men who wrote and ratified it, and the issues they faced in creating the Constitution.
During the debate over the ratification of the Constitution, there was significant concern that a strong federal government would trample on the individual rights of citizens--as had happened under British rule.