Self defense in unalienable (unalienable is the word used by the founders and so, is the word I choose to use).
Therefore, it follows, that if self defense of your life, liberty, and property is an unalienable right, then in order to effect that defense you should not be restricted in your means of using the common defenses of the day in the defense of your life, liberty, and property. (Note I am talking about arm's use in the defense of those unalienable rights, not for other purposes).
If you do restrict an individual in the defense of their life, liberty, or property, to such an extent that the common arms of the day are not available to them, you not only infringe their unalienable right to self defense (since those they face who would infringe on or take away their rights are most likely to be so armed), you also are threatening and therefore violating those other unalienable rights by extension.
That is exactly what the founders asserted in the 2nd amendment, therefore, "the right of the people to keep and bear arms shall not be infringed".
It is up to each state to decide.