Its a COBRAY SMG M11 (mac 11 9mm) That is not the silencer for it thats the flash suppressor/ forward handle.
It’s used for bump firing and is a nice extention to keep from shooting your hand offs.
Here is a video (not of me) for refrence on bump firing mac11’s [ame=“http://video.google.com/videoplay?docid=5951668400259938437&ei=S-EdSeayJYaYrQKXmanjBg&q=bump+firing+mac+11&hl=en”]Mac 11 MPA 930 9mm pistol machine gun bump fire[/ame]