The SG 552 comes from a family of rifles originally manufactured by SIG Sauer, now Swiss Arms (SG is an abbreviation for Sturmgewehr, or "storm rifle," not the manufacturer). These include the 550, 551, 552 and 553 assault rifles, all of which fire the 5.56x45mm NATO round. They are considered some of the best 5.56 rifles ever made.
In 1998, the SG 552 Commando carbine was introduced. It has a shorter 226mm (8.9 in) barrel (with an open, 3-prong flash suppressor) and gas tube, ventilated handguards, and a redesigned bolt carrier group that was integrated with the piston rod to form a single moving assembly. The return mechanism has been moved to the rear of the receiver housing and its recoil spring is guided in a way analogous to that of the AK-47: on a steel guide rod (later models feature a polymer guide rod) resting against the lower receiver's rear surface under tension of the compressed recoil spring. Like the SG 550/551, this model can accept rails and accessories enabling the use of optics. A long barrel version of the SG 552 known as the SG 552 LB incorporates a 346mm (13.6 in) barrel designed to fire rifle grenades and support a bayonet.