My daughter bought me an old German photo album - the majority of the pics are Maxim machineguns, but there was a pic of an MG34 in AA mode, as well as two pics of MG34's at the shooting range - on what looks like a cold day, the sheepskin coats look serious.
The photo-album was dated 1939 - but the photos themselves were dated 1941 on the reverse.
In AA config:
PS. Some MG shots, for the water cooled amongst you.