Gun rights cannot survive if they are identified as a solely conservative issue. Liberals must be encouraged to own guns, use guns in sport, and trained to use firearms in self-defense. This encouragement should include all forms of firearms, included semi-automatic weapons and machine guns.
If gun confiscation comes to America, for which the foundation exists if public will were to someday support it, it will come because it will not directly affect a sizable portion of the electorate. Contempt for liberalism is acidic to all liberty as it encourages factionalism. If guns are seen as solely the domain of one “faction” — conservatism — then when conservatism becomes unpopular, so will all the things associated with conservatism.
Most people with “molon labe” (come and take it) bumper stickers are inept to confront an armed force sent to confiscate their firearms. The best security is establishing in the minds of liberals and conservatives that gun rights are as sacrosanct a right as a free press. The best way to do that is assert the truth that a fully armed, and well trained, citizenry is the best defense against thieves that use force to take from you. Some thieves use a gun, and an army. There is no moral difference.
As for madmen whose desire to inflict pain is magnified by weapons, there are other means to prevent future Sandy Hooks. Gun restrictions and confiscations may work, but they intrude on too sacred a right to be palatable.