"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."
- II Amendment to the US Constitution
There isn't a lot of ambiguity to my eyes in this statement, but in this day in age where there are a lot of "grey" areas, I can see where some might get it confused. Its actually rather black and white, the idea that a Government derives its powers from the governed, was still a very new idea when it was written. The idea of a populist uprising against a tyrannical government was spreading, but the idea was still somewhat unproven. Almost every case that involved and armed uprising of individuals of lower station up to that point, usually ended with the words "mass slaughter". Indeed France proved that even when populations rise up, they can create tyrannies equal or even greater to the tyrannies they rose up to defeat.
The word hunting, or deer, or magazine is not mentioned anywhere in this statement. The Founders left some ambiguity in the Constitution deliberately because they knew things would change, but both the First and Second Amendments are devoid of such ambiguity. The Militia is not the National Guard, or even any State run armed force. It is a group of civilians, from a population or community that come together and train. Believe it or not you can actually classify the Boy Scouts of America as a Militia. These Militias, may be supportive of the Government, or even openly hostile, but in both capacities they serve as both a check, and a support structure for, the powers of the Government.
If there were a major disaster the BSA could roundly be counted on to help maintain community integrity, and assist in disaster relief efforts. They do not do this relief effort armed, but if the situation were truly dire enough they could. Sadly the more important function of these random (and sometimes not so random) associations, that become what we recognize as a Militia, is as a potential check against the day that the United States Government becomes too corrupt, or tyrannical to be called a Republic. Republics go bad. We have seen this with Rome. We've seen this with France. We've seen this with Germany. To think America is somehow immune to the trappings of power is foolhardy in the extreme.
I don't need to go too far to show how easily Republics fall. See if this sounds familiar. Large economic crisis, stock market crash, high unemployment, hostile foreign landscape, suddenly a popular figure emerges to show people that there is a reason that they're suffering, and it's not their fault. He leads calls for new government works programs, and his message of change spread throughout the country, giving the people new hope. It was the greedy capitalists who had betrayed them, but there was a way to make things right again. You might think I am referring to Barrack Obama. I'm not, that would be Adolf Hitler and the Wiemar Republic. It should fill you with a moment of pause to know that the exact same patterns we now face have been faced before, and others, no less human than us have made terrible mistakes in the name of security and economic prosperity. It should give you reason to guard jealously any power you have, lest the State feel that you somehow don't really need all those freedoms.
Imagine if Adolf Hitler had at his fingertips the sheer power and raw martial might of the United States in its current form. What would stop whole races from ceasing to exists? Once he had total power, nothing. It would be almost impossible to stop a tyrant once they had full power, so it would be important to block any potential power grabs as early as possible. It would not even need to progress to full flung insurgency if steps were taken early enough. Simply saying "no" when the tax collector comes for his share, and backing up those words with the ability to fight him off, would prevent a dictator from ever gaining control no matter how much they might desire it. Any nation's military when so vastly outnumbered and potentially firing on their own people would not be able to function very long.
See, it's not about President Obama being Hitler part II (though some people like to believe so). Its about what the US President could do if he or she were so inclined. The important question is "What If?" President Obama may want to restrict guns for truly noble reasons, he may believe in his heart that he is doing what is best for the country. But what if he, or someone else is not? What if someone elected after him has less scruples? Hand any man ultimate power, and they'll be tempted to fix just one thing, but it never stops there. It's never just one thing. There's never a silver bullet that cures everything, and often the "cures" come with problems of their own. President Obama is human. I'm human. I make mistakes, I often overlook the means because the goal is so important. If you examine your own life you'd probably find that you do the same thing. What's to stop you from doing something truly terrible? Only certain knowledge that if you cross some invisible line, people will stop you, be that other governments, your own people, or even your own family.
Like it or not we do need AR-15's and AK-47's. Like it or not, we do need "high capacity" magazines. Like it or not we do need nearly unlimited supplies of ammunition (as much to train as to actually fight). When they say "Freedom isn't free" it's not some trite phrase, to make you remember soldiers in some far flung battlefield, its as much to remind you that Freedoms always carry with them a price. That Freedom devoid of Responsibility is anarchy. That not paying attention to your Freedoms, and not minding your Responsibilities, or confusing Freedoms with Privileges has a cost. Sandy Hook, sadly is the cost when we are negligent in our responsibility, but what we have now is far preferable to what we could have should we so divorce ourselves from our freedoms.