My concerns with confication of privately held firearms during a period of civil unrest or other disaster is not with the state or local governments.
Frankly, they will have their hands full and do not have the manpower to go after Private owners who are not actively engaged in the situation.
My concern is with the Federal authorities in the case of a declaration of Martial law.
I have not seen any actual Operational Plans for Martial Law in the US. It is standard procedure to confiscate all privately held firearms when we take over a forgein country. Fairly effective in Macadonia totally ineffective in Iraq and Afganastan.