Regarding the 2nd Amendment. Couple things.
Quote from Thomas Jefferson that is actually on the Jefferson Memorial in D.C.
I am not an advocate for frequent changes in laws and constitutions, but laws and institutions must go hand in hand with the progress of the human mind. As that becomes more developed, more enlightened, as new discoveries are made, new truths discovered and manners and opinions change, with the change of circumstances, institutions must advance also to keep pace with the times. We might as well require a man to wear still the coat which fitted him when a boy as civilized society to remain ever under the regimen of their barbarous ancestors
1. Constitutional Amendments are not without ANY limits. For example the first amendment does not protect you from holding up porn images on a public street in front of an Elementary School. It doesn't protect you from the "yelling fire in a crowded theatre" example.
2. Our founding fathers were brilliant and set down really good base guidelines, but Thomas Jefferson's quote above is also him being forward thinking. Just let your mind go forward to 3D printers in the future and the possibility of any person "printing" weapons, any weapons at home.
3. Regarding the 2nd Amendment. "The right to bear arms". Unless you believe that means ALL arms, and the public should have the right to buy and own any "arm" the government has, then you are in fact for limiting the 2nd Amendment already. Unless you think Joe Public should have the right to go to a store and buy fully automatic weapons, rpg's or park a freakin' tank in their driveway then you believe in limiting the 2nd Amendment. Furthering that limitation to include more kinds of weapons / ammo is simply that.