Need to ID a Swiss Mag

[luscioman]

This weekend I picked up a shooter byf 41 and it came with 2 mags. I don't know much about Swiss mags and had no luck with my internet searches to gain more info on them. Anyway I would like to know whent he possible prodcution of this one was and the ball park value of it. As you can see in the pick it says "MADE IN SWITZERLAND" and it has the proof below it. The base is black plastic and one side has the swiss (+) proof as well. Thanks in advance for the help.