The Steyr AUG is an Austrian-made bullpup assault rifle chambered in 5.56×45mm NATO.
The Steyr AUG is a bullpup design — in other words, the firing chamber is located behind the trigger. This allows the weapon to have a far longer barrel in a smaller overall package, while also placing the action in the stock, utilizing space that is wasted in a conventional layout and also giving the weapon improved recoil characteristics. Other notable features include its translucent magazines, allowing the amount of remaining ammunition within to be determined with a quick visual inspection, its vertical foregrip and the integrated scope of early variants. The weapon can also be quickly and easily converted for a left-handed shooter.
The Steyr AUG is often incorrectly cited as the first bullpup assault rifle. However, this is not true, as the British-designed EM-2 preceded it. However, the AUG was the first bullpup assault rifle to see widespread use as the EM-2 was dropped after the prototype stage.