OK, so let's say that TEOTWAWKI happens. Both the I-Ching and the Mayan calendar predict the end of the world will be 21 December 2012...
Let's say instead that the US outlaws gun possession, punishable by death if found, followed by the most draconian police action ever, the systematic search and seizure (unwarranted) of every square inch of America to locate held-back guns.
Let's say you craftily have hidden some guns as described above.
What now?
It's not like you can expect to do anything with those few guns. I assure you, the average citizen will have turned theirs in (look to England for reference). The general gun-fearing Weinies never had any. And the well-prepared survivalists will have a few, but not enough to pose a threat to a (still well-armed) nation-state. All THEY will get is a brief and ruthlessly brutal example for the rest of the possible hold-outs of what happens when you have a gun in your "compound".
You won't be able to go target shooting, hunting, plinking, or anything else ever again in public. If you even used them to defend your life you'd be a criminal facing the death penalty for keeping a gun.
How long will you keep those guns if you dug them up? What would you do with them after they were outlawed as described above?
As has been stated over and over again:
"If it's time to bury them, it's past time to dig them up."
Luckily, I won't have to worry about this scenario because all of my firearms collection was recently lost in a bizarre boating accident.