When the Slovenian Army decided to adopt a new infantry rifle in the mid-2000s, the Arex Defense company decided to submit the F-2000 into the trials. The H&K G36 was widely expected to be the winner, but Arex had already been involved in making F2000 parts as a subcontractor for FN, and wanted a chance at a domestic-production rifle for Slovenia.
The one major hurdle was that the Army tender required the rifle to have a carry handle, which the F2000 does not. At the request of Arex, FN agreed to design a version of the rifle with such a feature, but balked at the extremely tight time frame required. So instead, Arex made their own new upper receiver for the F2000, with an elevated picatinny optics rail and a carry handle beneath. This was entered into the rifle trials and ended up winning. A contract for 6500 of the guns was issued, and they were delivered in 2006-2007. The final design was designated the F2000S by FN (not to be confused with the civilian-sale semiautomatic FS2000).
Thanks to Arex Defense for giving me access to this rifle to film, and thanks to Polenar Tactical for hosting me in Slovenia!