Correct me if I'm wrong but what mainly started it was Gaming ruled that the .999 needed to be on the silver not the rim. So, making the change they had to make new dies which were then changed to .50 silver content. Dies are not interchangable from .60 to .50 so as new designs or re-orders were made the new die had to be made. I think if you weigh the centers with the .999 on them you will find them .50 silver. Jeff