In 1925, the German military began a series of secret SMG trials at the Kummersdorf testing grounds. One of the participants was Heinrich Vollmer. He was funded directly by the government for his small arms R&D until 1930, and iteratively developed his design until it went into large-scale production as the Erma EMP. What we are looking at today is the VMP 1930 pattern (a C&R transferrable example). At this stage, the gun had most of its final design elements, including a traditional box magazine, self-contained recoil spring system, and bare barrel. It also had a collapsing monopod in the vertical front grip, which would be later discarded.