WHICH GERMAN ARTILLERY PIECE IS THIS, and CALIBER?

[bldrhouse]

German press photo of the Atlantic Wall; unfortunately, no location.

 

Any idea what artillery piece is shown in the photo?

 

 

fyi, the caption reads:  

 

[Proud Kraut]

The round 2-chamber muzzle break of this gun seems to have similar features as the one of the Soviet 76 mm divisional gun ZIS-3. The Wehrmacht captured several hundreds of ZIS-3, one of the best anti tank guns in WW II. For several reasons captured guns were prefered used in fortifications like the Atlantic wall. So maybe it´s this gun but I have to do more research.