I have a very old cartridge case that was handed down to me from my father and his father before him. It very closely resembles a style from the civil war era but I cannot find anything like it anywhere. It is heavy leather with the belt clips on each side that are metal. The only design is that of a small brass cannon on the front flap. When opened, there are two big slots (~4" long, 2" wide). The only markings are on the back on teh front flap on the inside; it says "WD" with an arrow pointing up. Does anyone have any idea of what/ when this is and it's worth?