That's a very nice case kz11gr.
The following link gives some details about the Mauser 213/30 and the Mauser 213/20 plus the Aden 30/20 cartridges (made of brass) that were developed from the Mauser.
I don't have the belted version of the Mauser 213/20 but the non belted version is shown.
Dave.
http://www.bocn.co.uk/vbforum/mauser-213-t27629.html?t=27629&highlight=mauser213[/QUOTE
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Thank you Dave
My first impression was that it's a post war french fabrication from the German 213/20 , with some modifications.
But may be post war U.S too ...
.