The Steyr ACR was a prototype flechette-firing assault rifle built for the US Army Advanced Combat Rifle program of 1989/90. Although the Steyr design proved effective, as did most of the weapons submitted, the entire ACR program ended with none of the entrants achieving performance 100% better than the M16A2, the baseline for a successful ACR weapon.The Steyr ACR has some superficial resemblance to the Steyr AUG, although it is rounder and the barrel is covered for almost its entire length, as opposed to the AUG where much of the barrel was exposed. Like the AUG the ACR is a bullpup design with the 24 round magazine located quite close to the buttstock of the gun. The stock was split from the magazine forward to a location just below the sights to open for cleaning. An optical sight was included as a standard feature.