No Swiss cross banner ?
I'm not sure it's a Swiss Commercial.
The 1920 Swiss commercial lugers were built on 1906 frames with a grip safety (I don't see a grip safety on this photo).
I have a Swiss 1920 commercial S/N 2011 "L" and I think it was assembled in 1921 w/ a German barrel (95 mm).
There is a very typical Swiss luger on this link today: Swiss Luger
I thought you might be interested in reading this web page:
http://forum.lugerforum.com/showthre...ferrerid=12799