Really unique rifle from East Germany. It was prototype that combined StG44 internals and G3 look and was chambered in 7.62x39mm. It was one of those really weird guns that they made during Cold War when they pushed for assault rifles instead of classic rifles.
There are not much info or images of that rifle, really only one article from Czech Magazine that contained only 4 low quality images, but that was enough to get overall shape of gun.