That's awesome! What is the significance of the "circle 11"? Mine has it, and it was made in 1952. If the box is correct it was made by Radom.
The first year or 2 of production had the "FB" logo stamp. After that they fell in line with the other combloc countries by having their country code in a circle as their arsenal stamp. Hungary was a circle 02, Bulgaria was a circle 10, etc. It was a standard used.