The MSAR STG-556 is a bullpup assault rifle, similar in design to the Steyr AUG, that is gas-operated with a rotating bolt. It's designed as a modular weapon system that can be quickly configured as an assault rifle, carbine, or submachine gun. The STG-556 is chambered for 5.56x45mm NATO ammunition and can use M16-style metal or aluminum magazines. It features a 1:7-inch-twist barrel with a chromed bore and comes with a 10-inch MIL-STD 1913 top rail optic rail and backup iron sights