The Second Amendment:

" 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."

It takes two things into account; 1) well regulated Militia and 2) rights of the people to keep and bear Arms without infringement. So after reading do you really think it has no purpose in relation to the government? Really?

People of the United States are the Militia and don't realize it, in my state we have a Citizens Militia Manual. This is important because to be a part of an unregulated Militia could put you in serious trouble. But this does not mean they have the right to infringe on keeping and bearing Arms.

The Courts have reasoned that the Amendment's prefatory clause, i.e., "[a] well regulated Militia, being necessary to the security of a free State," announced the Amendment's purpose, but did not limit or expand the scope of the operative clause, i.e., "the right of the people to keep and bear Arms, shall not be infringed." Moreover, the prefatory clause's history comported with the Court's interpretation, because the prefatory clause stemmed from the Anti-Federalists' concern that the federal government would disarm the people in order to disable the citizens' militia, enabling a politicized standing army or a select militia to rule.

Source FindLaw (Second Amendment - U.S. Constitution)

"Single acts of tyranny may be ascribed to the accidental opinion of a day; but a series of oppressions begun at a distinguished period, and pursued unalterably through every change of ministers, plainly prove a deliberate systematical plan of reducing us to slavery." - Thomas Jefferson

"When the government fears the people, you have liberty. When the people fear the government, you have tyranny." - Thomas Jefferson

The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in Government. - Thomas Jefferson

"The militia shall consist of the whole body of people, minus public officials." - George Mason

If the representatives of the people betray their constituents, there is then no resource left but in the exertion of that original right of self-defense which is paramount to all positive forms of government

… Federalist Paper No. 28, Alexander Hamilton