I realize that this discussion should be labled "to be used for educational and recreational purposes only," but to play the game a bit further: Who here believes that those forces that would confiscate our guns would announce-- in advance-- that 'police units will be in such-and-such neighborhood on this-and-that date and all citizens are expected to turn in their guns at that time?'
Nobody, right? If gun confiscation were to happen, it would be as completely without warning as the authorities could manage. The police would have lists of specific addresses and the guns to be found there. If SKS #XXXXX wasn't found at Joe Blow's house, there'd be a number of questions Mr. Blow had better be prepared to answer. So, buying guns 'off_paper' is going to give you (if not the previous owner) some breathing room.
But, there's another thing to think about now. Remember a recent story about police using the tips generated during the D.C. sniper saga to catch illegal gun owners? Well, now Oregon, and soon other states, wants to track vehicular milage (for tax purposes, of course) using the GPS locator beacons in cars. Who's to say they won't be able to find the general location of the cache you've driven to?
Too much trouble, you say? We're talking about government here, and if the government should become totally tyranical, nothing would be too much trouble if they could find a gun or two, especially if the owner could be publicly executed as a deterrant to others. That was the way Hitler did it, as did Stalin and Pol Pot and... etc., ad infinitum.
There are no perfect hiding places. If one person can think of a place to hide something, another can think of the same place to find it. The worst places are close to home. If the police come for you, they'll do it in the middle of the night and use the next three days to search every square foot of your home and property. They can be very thorough.
If you choose to bury something, give the idea a lot of thought before you ever buy a piece of pipe. You'll need to know exactly what to bury, how to bury it, how to get it there without being seen or traced and how to retrieve it when you decide you need it. None of those steps can be left out. There are no shortcuts to survival.