Sandy Hook is just one reason why I don't own a AR-15 or other semiautomatic firearms. I'm of the opinion that no civilian (police included) needs a semiautomatic.
But I've got a .30 lever-action rifle. I usually only load it at the range. I usually only fire it at the range. I've never even aimed my weapon at another human being, despite occasionally being tempted.
I see no reason why I should allow my rights to be abridged because other people abuse theirs. The needs of the many might outweigh the needs of the few, but I do not accept that they can outweigh the rights of the individual.