It's not about the Constitution being outdated. It's not about muskets vs. AR-15s. It's about liberty! You cannot compromise the long-standing idea of individual liberty -- it has no expiration date. The smallest of compromise only leads to larger degradation of the premise in which the Constitution was written and leaves it open to further "interpretation" when the next regime takes office and governs by opinion instead of principle.
Republicans and Democrats alike will point to the Constitution and scream about freedom of speech and religion and a host of other causes, but in a heartbeat will enact bills like the Patriot Act, NDAA and, now, gun "control," and do so saying, "Well, the Founding Fathers didn't plan for this." Yes, they did. They planned for you . They planned for people to try and manipulate the system so they could garner power and that is why they wrote the document in its absoluteness.
It amazes me that so many people will justify unconstitutional drone strikes in sovereign countries, killing thousands of people and hundreds of kids, by saying, "Freedom has collateral damage," but will condemn my freedom to have the gun I want because sick criminals decided to use a gun to attack innocent people. The hypocrisy is so dumbfounding, it's indefensible.
Semper fi, to the oath.