SIG SG 550

The SIG SG 550 is an assault rifle manufactured by SIG Sauer AG (formerly a division of Schweizerische Industrie Gesellschaft, now known as SIG Holding AG) in Switzerland. "SG" is an abbreviation for Sturmgewehr ("assault rifle"). The SG 550 was co-developed by SIG Sauer AG and the Italian firearm manufacturer Beretta; it is based on its predecessor, the SIG SG 540, chambered in 5.56×45mm NATO.