...Winter War version. The Castle's semi-auto M31 Suomi submachinegun. [This pic embiggens] As is common with weapons of it's pre-WWII era, the thing is built like a tank, and massive. The only real cosmetic difference between this one and one in original condition is this one is parkerized vice blued, and has an extension welded to the barrel in order to meet legal requirements for barrel length, so as not to have to be registered as a "short-barrelled rifle" under the NFA, National...