This is one of the abovementioned 57 mm guns, which was at Fårösund batteries. The picture has been made in a former military camp of 3rd Regiment (KA-3) of coastal artillery of Sweden (Kustartilleriet) in the village Fårösund.
Kustartilleriet (KA) emerged in 1902 from parts of the Archipelago artillery and Marines and was an integral part of the Swedish Navy.