A force that is in a fight, or which anticipates someday being in one, has a need for reserves. Unless the mere existence of those reserves is specifically intended to have a deterrent effect, it is best that the reserves remain unknown to the actual or potential enemy (and even if that's the goal, those reserves need to be secure from seizure or destruction). A good example of this is the Soviets, who had over 100 divisions that the Germans never knew about before invading in 1941. When the Germans had destroyed, captured or made combat ineffective the 180 divisions that their intelligence said the Russkies had, while the Russians were still fighting like mad, they realized that they were in deep trouble.
In a situation with guns in civilian hands, there are clearly records out there about most guns sold in the last 38 years, plus any older ones that were sold as used through FFLs. In a worst case scenario, one would have to assume a knock on the door by a dozen or so vested and well-armed individuals who had a list of all of your guns. Then is not the time to say that they were lost or stolen or destroyed or sold, etc. - it is the time for handing them over or dying along with your family. If, however, you wanted to live to see your kids and grandkids grow up, and to see them live in freedom, you'll have previously acted like a 2-legged squirrel and put something away for a rainy day. Since acting alone is usually less effective than acting in concert with like-minded people, it'll be time to organize and make plans - and only later will those plans be implemented and need equipment to do so. This'll also be a time for keeping one's head low and not coming to anyone's attention - hence the need for secure reserves that are available much later than when a bunch of JBTs comes to your door.