The Steyr Aug is a 5.56x45mm NATO bullpup rifle developed in 1977. It is gas-operated from a closed bolt position and was designed as a modular weapon system. It can be configured into a rifle, a carbine, a sniper rifle, or an open-bolt squad automatic weapon. The quick-change barrel forged in Steyr Austria, gives it increased precision and durability. It was adopted by the Austrian Army in 1978 and later used around the world by other military agencies.