Some speak about self defense as a purpose for gun ownership as a reason making other parts of the constitution applicable. To this I want first to say that you need to prove not only real but also unique dependency on that ownership. This is not like saying the government can suppress a newspaper because you can express your opinion on TV. There expressing an opinion in newspaper is still an expression of opinion even with the existence of other alternative. Here, on the other hand, the creation of the defense part in the self defense claim needs the absence of other solutions. It is not enough that a gun enables a person to eliminate a danger for its ownership to be supported by self defence claim.
The second thing is that you also have self defense claim for the people under the legislation in question. You have individual self defense claim against group self defense claim. It is not like anybody would legislate against gun ownership just because they look ugly.