I would like to identify the maker of my grandmother's silver plated tea set. A four-piece set plus tray. All the pieces are stamped with a delicate crown, below which are the initials "S R S" inside a rectangle. Below that are the numbers 1300, 1301, 1302, or 1320, depending on the piece. I've tried to find this hallmark on line with no success. The set is probably 70-80 years old; she bought most of her table service items in the 1940's and 50's.
Thanks for any insight you can provide.