Today’s rifle is not quite an Austrian military StG-77, but it is virtually identical. This is one of the commemorative rifles sold by Steyr, which has been rebuilt with military parts and is a registered dealer sample machine gun (which is why I can show you the complete full-auto functionality in the trigger group.
The AUG (Armee Universal Gewehr) was one of the wave of bullpup-style military rifles developed and adopted in the 1970s, along with the British SA80 and French FAMAS F1. The AUG embodied a number of very forward-looking elements in its design, including extensive use of polymers (including the entire fire control group), a completely modular barrel, and standard integrated optical sight (albeit one considered obsolete today). Mechanically, the rifle’s operating mechanism is a derivative of the Armalite AR-18, as are many other service rifles from this period.
Special thanks to Bear Arms in Scottsdale, AZ for providing this rifle for video!