I think the whole "problem" with the question you ask Col0016 is the premise that you're going to "sell" your precious metals for fiat currency when the SHTF.
To my mind (and I will stress, this is my personal opinion only) that isn't the objective of holding PM's assuming you're planning on a crisis situation (I do believe that the SHTF one day, and agree that holding PM's is an "insurance" against this).
One has to stop thinking in terms of the overall economic paradigm we have today. You will not be trading your PM's for fiat currency if SHTF, you will be trading them for other assets that would be unobtainable otherwise (presumably because fiat currencies have collapsed, or have been hyperinflated to oblivion).
If you honestly believe the day will come where the SHTF, then you have to prepare on several levels. Firstly, you don't really want to be trading your PM's for tomorrow nights meal - you will want to have an appropriate level of non perishable food on hand to withstand shortages that are extremely likely to occur in a crisis situation. Ditto for drinking water, cleaning (both personal and household), and various other aspects of your daily life that - at the moment - are satisfied by "just in time" type purchasing from your local supermarket.
Beyond that, you have to stop and think about "what will come next". Everyone's personal opinion of what will happen when the SHTF is going to be different, and this will determine your personal view on how and what to prepare, and when.
Once you have various things sorted (that is, a food and water supply, methods to prepare that food that are not reliant on external energy input from the electricity or gas grid), one turns their attention to what will happen after the SHTF - that may be the week, month, quarter, half year or year or more after the event. How do you give yourself a "head start" in the "new" economy? One of, if not the *ONLY* ways to do this is to find something that is rare, impssible to artificially duplicate, hard to obtain, and will be - one day - in demand again. Here is where precious metals step in (with my own bias that some precious metals are better than others left aside). It is in the "after SHTF" scenario that the gold and silver you set aside today (which would otherwise have been held as cash in the bank - potentially up for grabs by any government, and reliant on the stability of a banking institution that owes depositors considerably more cash than they have on hand) will become your "preserver of wealth".
Take a look at any major SHTF scenario in years gone past - WW1, WW2 etc - those that had gold & silver always did very well, they were able to obtain things beyond the wildest imaginings of the population at large - the stories are out there, my parents, thankfully, were able to educate me on this first hand (no, they did not themselves hold precious metals, but they lived in Germany through WW2, and saw first hand what those very few citizens who did hold some precious metals were able to do with them once the war was over).
