True,
Although-- like you wrote-- the direct ancestor of the CEMTE and then the H&K G3, the prototype STG45M (with the delayed blowback mechanism), actually looks quite different than the more commonly recognized "the first Assault rilfe" STG44/MP43/MKb.42(H) with the piston and tilted bolt mechanism
[התמונה הבאה מגיעה מקישור שלא מתחיל ב https ולכן לא הוטמעה בדף כדי לשמור על https תקין:
http://world.guns.ru/assault/stg45m.jpg]
http://world.guns.ru/assault/stg45m.jpg
From
http://world.guns.ru/assault/as93-e.htm
German development of assault rifles did not stop with the adoption of the Haenel / Schmeisser "
Sturmgewehr"
Stg.44 rifle. ....... Most interesting among these was the Mauser design, usually credited to Wilhelm Stähle and Ludwig Vorgrimler. Mauser devised a version of the retarded (sometimes also called delayed) blowback system. In this system, there was no gas system and piston, and no rigid locking. Instead, rollers were used to retard the opening of the breech until the chamber pressure dropped down to safe levels. This system was factory designated as “Gerät 06H”, and by early 1945 was officially type-classified as Stg.45. ....
During the early 1950s Vorgrimler moved to Spain, where he participated in development of the
CETME assault rifles, which led directly to the famous Heckler & Koch family of small arms, including the
G3 and other assault rifles, submachine and machine guns, all featuring the same roller-delayed blowback system.