The rolling and stamping requires a much heavier press, think about it, you have to continuous cast the metal, roll it to a precise thickness and use one big mother punch press to stamp out blanks. You then have as much as 15% stamping waste to remelt and reprocess. Then you have to stamp the blanks with your name, the weight, and the purity.
By pouring fine shot and accurately weighing the shot out it can be melted into specifically sized ingots by 2 different methods. First is to pass the mold with a precisely weighed quantity of shot in it through an atmospheric furnace where the bars cool under an atmosphere and emerge beautifully unblemished smooth and clean. The down side is the furnace is most efficient when running large quantities of bars, as in big refineries, large operating costs for the little guy.
The other option is to melt in a clean crucible with no flux under a reducing flame to burn off any oxygen (especially necessary for silver) and pour into a specific sized mold on a table where the cooling is controlled and again under a flame. The slow cooling makes an attractive bar.
Both of these methods produce a bar which has to be stamped in a press with a die for the specific size you are producing. You need to have your name and logo, the weight of the bar, and the fineness. Also a serialized number traceable back to your analytical results for the batch the metal was refined in. This gives credibility to your assay claims.
If you mark the bars .9999 and they're not, you won't be in business for long. Using the method of weighing out shot makes this easier because before you shot the metal, you sample the melt lot for assay. Then your serial numbers trace back to that assay.
I doubt that the government checks for quality but I guarantee your competition will, not a good place to cheap out. It is a tough market to break into, you are going in as an unknown commodity so people buying from you are taking a chance. If you are successful, your competition will be laying in wait for you to produce some under assay product. These guys play hardball. You need a solid protocol to track purity and impeccable record keeping.
