Star Si35 SMG
The 35 series are first generation, full-stocked, tubular receiver, straight blowback guns. They fire from an open bolt. The three are basically identical weapons, varying only in the firing assemblies and rates of fire. The RU 35 fired at 300 spm and the TN35 at 700 spm. The Si35 fired at semi auto or either of the rates, but only by setting an amazingly complex configuration of two multi-position switches. These saw some domestic service in the Spanish Civil War, and were offered for sale to the US and British in WWII, but were never bought due to the needless complexity. More information at: http://www.donttouchme.com/star
Picture and information courtesy of: Steven Hoober