Prolegomena: There are two guns in my house — 12-gauge shotguns. They are in a gun safe; each has a trigger lock; the shotgun shells are stored elsewhere. I hunt, and I fear guns. They are breathtakingly powerful.
Premise 1: When you live in a society with other human beings, you necessarily give up some of your freedoms. This is incumbent upon each individual citizen in order to reap the benefits that society offers. For example, you have the benefit of driving a car, an incredible perk of modern society: it gets you places far more quickly than your feet, adds billions of dollars to our economy because of its efficiency, etc. However, you can’t drive a car anywhere you want; you must stay on the paved roads — indeed, you must stay on one half of the paved roads. If you cannot abide by these rules, you abdicate your right to drive a car.
Premise 2: The Bill of Rights is an anachronistic document, and it therefore must be interpreted for our present situation. It was written at a time in which firearms were not nearly as powerful nor accurate as they are now; today, firearms can do exponentially more human damage than they could in 1789. It was written in order to protect against a monarchy or military dictatorship; under the command of the president, the US military is the most powerful force in the world by an order of magnitude, and could therefore easily put down any populist uprising.