Hi Walt,
Because we are talking about silver strikes, and if a .999 center is actually .950 would be less than a buck difference, nobody here probably cares much about it. And, it's not that big a deal. If you are talking about having a few thousand strikes, it's a little bigger deal. But since the laws have been tightened up a bit since strikes were first made, I think anyone selling large lots of strikes would be smart to sell as silver stamped .999 fine rather than to advertise as .999 fine silver.