Dwight and Pete:
the only marks are beside the serial number:
Swiss cross which is the army accaptance normally
and
Swiss test firing stamp "PB"
It is a 7,65 Para caliber.
http://forums.lugerforum.com/lfupload/beschu_copy1.jpg
http://forums.lugerforum.com/lfupload/right_copy2.jpg
http://forums.lugerforum.com/lfupload/sunburst.jpg