Jacob Duygu

Jacob Duygu ( 1993 – October 2021), known online as JStark1809, was a German firearms designer and former Bundeswehr soldier. He is best known for designing the FGC-9, a semi-automatic 9mm carbine that can be manufactured using a 3D printer and widely available parts.

Early life Duygu was born in Germany around 1993 to Kurdish parents. He lived in Hannover before moving to Völklingen in the summer of 2020, where he lived in relative isolation. During his service in the mid-2010s, he received basic firearms training, including use of the G36 assault rifle. However, as a member of a non-combat logistics role, his operational access to firearms was limited to training exercises, and German law prohibited him from owning one privately despite his military experience. Duygu left the Bundeswehr before 2018. The firearm uses a 3D-printed polymer lower receiver, an electrochemically machined barrel, and commercially available springs and hardware store parts.

The design was publicly released on 27 March 2020 through online file-sharing platforms. An updated version, the FGC-9 MkII, was developed by Duygu in collaboration with designers "3socksandcrocs" and "Ivan the Troll" (Ivanthetroll), with initial announcements in October 2020 and full files released on 16 April 2021 via DEFCAD and Odysee by user "The Gatalog". The MkII incorporated several refinements to simplify construction and enhance reliability, including a full-length Picatinny top rail for optics and accessories, an H&K MP5-style charging handle, an enclosed ejector design, an integrated sling loop, a more durable bolt, and a switch to metric hardware for global parts availability.

Several days later, in early July 2021, Duygu was found dead in his car. An autopsy conducted by Saarland authorities concluded that the cause of death was consistent with natural causes, most likely a heart attack, potentially exacerbated by stress and a pre-existing congenital heart condition. No evidence of suicide, foul play, or external injury was found. The exact date of death has not been publicly disclosed, but it occurred within a week of the raid.

The timing of his death led to speculation within online 3D-gun communities, though German authorities and subsequent investigations found no causal link between the raid and his passing.