It was decided that the calibre would be 130 mm, since the mobile coastal artillery used towed guns of same calibre (130 K 54). A prototype was constructed on the island of Isosaari in 1980, where test firing was conducted until 1983.
A decision was made regarding the caliber of the gun, which would be set at 130 mm, as mobile coastal artillery employed similar guns with the same caliber. A test model was built on the island of Isosaari in 1980, and testing continued until 1983.