http://www.quarryhs.co.uk/SEMAGL1a.jpg
Found this photo on the net while searching for references to Swiss aircraft mounted mg or cannons. The end fittings and the ring-mounting look similar to the device on MG1. Not sure about the scale on the MG1 photo.
...geoff
Ref: Tony Williams & Emmanuel Gustin Cannon Pioneers web-page - Oerlikon L cannon on flexible mount.