Unidentified austrian machine pistol

An early SMG of an unusual design, dating to around the World War I period. The last one left is in the Canadian War Museum in Ottowa. The maker is unknown and pictures are scarce. That's why I wanted to low poly model this gun with internals.
The Vertices are around 3'300 and the render is in cycles. The number of Vertices and the few reference photos I had for this model, definitely gave me a little challenge.