Seeing gold bars in Fort Knox (assuming they aren't gold plated tungsten http://agmetalminer.com/2009/12/03/fake-gold-bars-discovered-in-hk-lbma-approved-vaults/) is not the same thing as knowing who owns them. That's something a proper audit should find out. When a large quantity of gold is sold it is usually not moved out of its vault, instead they just change the label of who owns it. We know the government leases out gold, and the traders who lease the gold sell it (as part of a carry trade). The traders are supposed to return the gold eventually but do they? That's one of the things an audit should find out. There is also the issue of the quality of the gold. Before Nixon closed the gold window foreign countries could redeem U.S. dollars for gold at a fixed rate. This led to a large outflow of good delivery bars. We may find that what's left over is the dregs, maybe 22 karat rather than 0.995+ fine.
Security reasons??? Yet you can tour and see millions of dollars being printed at the bureau of engraving & printing. Why arent the security reasons enough to stop the tours of where the money is printed? Something seems fishy. http://moneyfactory.gov/tours/washingtondctours.html