The U.S couldent keep up production because everyone would simply be hoarding as much as they could. Prices would decrease at first because of supply but suddenly skyrocket.
Lets say the coins were just like what we have now size and look but only a percentage of silver that would be equivalent to the face value of said coin.
These "laws" authorizing them as such aren't actually real laws because it is already totally legal for shop keepers and individuals to accept silver coins like ASE's as payment. To my knowledge, none of the state governments authorizing these coins as "legal currency" are actually accepting them as payment for taxes and such. So these aren't real "laws" as much as they are propaganda in my opinion.