The SIG SG 551 is the carbine variant of the SG 550, fitted with a 14.3-inch barrel while retaining the full SG 550 folding stock and magazine coupling system. Issued to Swiss Army vehicle crews and paratroopers. Like all SG 550-family rifles, it is built to exceptional Swiss quality standards. Type: Rifle Action: Semi/Full-Auto Caliber: 5.56x45mm Capacity: 20 Year introduced: 1986, Switzerland Weight: 123.2 oz Overall length: 31.7" Status: Active Military use: Yes Intended use: military, special_operations