I referred to this thread when researching this piece and according to it this piece exhibits the qualities of an original piece.
SS Gruppe West tinnie
Just noticed acouple things. Your skull is different. As well as your XI and other numbers. The background, bubbling, and numbers seem to be much more "crisp' than the known original. That being said, it seems your tinnies metal is different then the tinnie in the thread you posted. Maybe a different varient? I'm not commenting on this items authenticity, just what I see when comparing. Good luck.
Yeah. I had noticed that well. I guess I'll stick it in the ??? box.