The German 5 cm gun, as used in the Panzer III was later widely used in many field fortifications. You could find them on all locations, France, Netherlands, Belgium.
|5cm gun position with Munitionspanzer I|
|5 cm kwk Bunker with Panzer I|
|Atlantic wall in 1/144|
The Bunker with the 5 cm kwk gun can be bought in my Shapeways shop: Bunker