Only under times when normal political conditions exist. Not in the case of a national catastrophic disaster. Think multiple terrorist WMD attacks on major US cities. For that not so happy instance the groundwork has already been laid and the long string of Executive Orders have been in place since the 1980s; authored oddly enough, by LTC Oliver North. I'm sure he could not foresee the eventual use to which his plans may be put. Do a Google for REX84 and read the area on Executive Orders in case of such an emergency. Another, harder to find document that seems to have been purged from the net somehow is a FR document titled FEMA: THE DARK UNDERBELLY which will scare the willies out of you. It's fact, too. The REX84 document is full of hysterical ramblings but there are more than a few grains of truth there, too. But the DARK UNDERBELLY is just full of facts, which is why "somebody" may have been dedicated enough to purge it from active circulation.
I once asked my aging Father in Law, holder of the Navy Cross from WWII about the possibility of caching our guns from such a governmental intrusion. He said to me: Son, the time comes that you have to bury your guns to protect them is the exact time you'll be needing to dig them up for use! That made a lot of sense to me. Still does. I might place them will nilly around the country side for future uses but as far as a long term cache? Naaaaah.
Reserves, man, reserves. If, theoretically speaking (of course), someone had guns that the gov't didn't know he/she had, then when they were forced to give up what they were known to possess, they wouldn't be naked to the world (at least not for more than a few hours or days).
This lesson is derived from the Russians in WW2 - have so much secreted away that the enemy doesn't know about that when it captures/destroys everything it thinks you have, you surprise them by having yet more. This is the only prudent course, IMHO, for ALL concerned with this issue.