East Germany, in the period before the collapse of the Berlin Wall, was short of foreign currency. In an attempt to generate cash for imports Wieger developed an AK-clone chambered in 5.56mm NATO. It was apparently very reliable. The collapse of the wall saw the demise of the company which found itself in direct competition with West Germany’s H&K.
Inter Ordnance manufactures an AK rifle which looks like the STG, although the resemblance is surface deep. Until Sven emailed me the below photos, I had not seen pics of the real STG 90x series.
[ Many thanks to Seven for emailing me the history and photos. ]