The Second Amendment, which was adopted on December 15th, 1791 as part of the first ten amendments to the Bill of Rights of the United States Constitution, states:

"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."

Our Founding Fathers crafted the words to this amendment very deliberately, critically, and precisely to leave an unquestionable interpretation and legacy for future generations.  Let's analyze these words a phrase at a time.

"A well regulated militia,..."
  Our Country just broke away from Great Britain.  Our Founding Fathers understood first hand that our new government might eventually some day become just as tyrannical as Great Britain if it had the authority to disarm and control its citizens like the British attemped to do.  The Revolutionary War against Englad [having a "standing army"] was fought and won by ordinary male citizens, not professional soldiers.  During that time, all male citizens were required to own firearms.  James Madison, the father of the Constitution, said in 1789 that a well regulated militia is composed of a body of the people [a citizen army, not National Guard], trained to arms.  In order for militias to be effective in battle, they therefore need to be well regulated through training and drilling with unrestricted access to firearms.  An example of this were the Minutemen at Concord and Lexington who drilled on fields in preparation for war.  George Mason, from whom the Bill of Rights was composed, wrote, "it is the duty of all citizens to practice justice, moderation, temperance,..." and defines the militia as "the whole people, except for a few public officials."

"...being a necessary to the security of a free state,..."
  Our Founding Fathers wanted explicit guarantees to certain rights to prevent any possible and potential encroachment by the federal government.  This amendment grants and unconditional right for private citizens to bear arms for not only self defense, but also for rebellian when a tyrannical government turns oppressive.  Sir William Blackstone, and English scholar and justice, described this right as supporting the natural rights of self defense, resistance to oppression, and the civic duty to act in defense of the state.  In addition, Thomas Jefferson is quoted as sayng that "a little rebellion every now and then is a good thing."

"...the right of the people to keep and bear arms,..."
  Much legal discussions, opinions, arguments, and decisions have evolved over the last 2 centuries in the interpretation of this phrase.  However in 2008, the United States Supreme Court handed down a landmark decision in the case of District of Columbia v Heller, expressly stating that the amendment protects an individual right to possess and carry firearms.

"...shall not be infringed."  The United States Constitution does not delegate the regulating of firearms to the federal government.  In fact, this amendment clearly restricts federal power from infringing on the right of the people to keep and bear arms, this means any firearm or any ammunition.  Zacharia Johnson, a delegate to the Virginia Ratifying Convention, declared that "The people are not to be disarmed of their weapons.  They are left in full possession of them."  Full possession.  Not some.  Not most.  But, full possession of their weapons.  The federal government was to keep it hands off entirely.

In conclusion, any federal legislation regarding gun control is essentially unconstitutional.

Resources:; Tenth Amendment Center;; Virginia Declaration of Rights [1776]; West's Encyclopedia of American Law, edition 2, Copyright 2008 The Gale Group, Inc.; Wikipedia