If you search for +larsen +winterros in www.google.com/patents
you will find the United States patent for this gun including some very good detailed drawings of the mechanism. This link may work: http://www.google.cl/patents?id=uOJA...terros&f=false
According to the patent, Larsen was from Norway and Winterros from Sweden, but by the 1880s both were resident in Liege, Belgium. They took out patents for the mechanism in Belgium, England and the United States.
So, where was this gun made - what is the evidence for Denmark or Norway?