The Star Si35, RU35 and TN35 are Spanish submachine guns.
The Si35, RU35 and TN35 were developed in the mid 1930s by Star Bonifacio Echeverria. Somewhat little information about the history of the weapon is available other than this, including the date of discontinuation and who it was used by.
The Si35, RU35 and TN35 are standard blowback operated submachine guns. All three weapons are visually identical and mechanically very similar, with the same layout and control setups, with the only discernible differences between the Si35, RU35 and TN35 being the rates of fire of all three weapons. The RU35 had a rate of fire of 300 RPM, likely due to a bolt weight, the TU35 had a rate of fire of 700 RPM, while the Si35 had a unique capability for weapons at the time: the ability to toggle between two rates of fire. This ability was not seen on many weapons before that time, or after, for that matter, with the most famous weapon having a variable rate of fire being the Browning Automatic Rifle.
The Si35 had an overly complicated control setup, with two levers mounted on the left of the weapon. The forward lever acts as a selector switch, which switches the weapon between semi-automatic and fully-automatic, while the rear lever acts to reduce or increase the rate of fire of the weapon and doubles as a safety; how it is able to toggle between both rates of fire is not known, though it is assumed it could be similar to how a Browning Automatic Rifle's method of doing so.
The Si35, RU35 and TN35 use a complicated delayed blowback system, where a two-piece bolt locks the bolt head to the receiver on the early stages of recoil. Sights were adjustable from 50 meters up to a very optimistic 1000 meters, similar to the SIG MKMO. The weapon has a wooden stock, and the weapon's barrel is fitted into a cooling jacket with a muzzle brake up front.
Selectable rate-of-fire variant.
Variant that fired at 300 RPM.
Variant that fired at 700 RPM.