The SG 551 carbine has a short pattern 363 mm (14.3 in) barrel, gas tube and piston
compared to the SG 550. The SG 551 series rifles have a 466 mm (18.3 in) long sight radius.
The handguards were also changed and the bipod removed. The SG 551 cannot be used
with a bayonet or fire rifle grenades. The SG 551 comes in several specialized variants
designed for use with security and special forces. Among those variants are
the SG 551-1P police carbine (designed to engage point targets out to 300 m;
equipped with a Hensoldt 6x42 BL telescopic sight and detachable cheek riser),
the SG 551 SWAT carbine (coated with a corrosion-resistant finish and equipped
with an optical sight mount used with a wide array of sights, and can also accept
mission-critical accessories such as a bipod, laser pointer or tactical light) and
the SG 551 LB carbine with an extended 454 mm (17.9 in) barrel that enables
the use of rifle grenades.
Slovakia: The Slovak Police Utvar Osobitneho Ur?
enia (special assignments unit) utilizes the SG 551 SWAT carbine
Argentina: GEOF counter-terrorism unit uses both the SG 551 and SG 552 Commando.
France: The SG 551 and SG 551 LB carbines are used by some specialized units of
the French Army and the GIGN counter-terrorist unit.
Germany: The German Federal Police's counter-terrorism unit GSG 9 and
the Spezialeinsatzkommando group of the state police both employ the SG 551
and SG 551 LB carbines in a variety of roles.
India: COIN Ops; small numbers employed by the MARCOS.
Jordan: Jordanian police use the SG 550 Sniper in small numbers.
Romania: Small numbers of the SG 551 LB employed by the 307th Marine Battalion.
Serbia: SG 552 version used by the SAJ anti-terrorist unit.
Slovakia: The Slovak Police Útvar Osobitného Určenia ("special assignments unit")
utilizes the SG 551 SWAT carbine.
Spain: National police GEO special operations group uses both the SG 551 SWAT
and SG 552.
Switzerland: As of 2009, the SG 550 is the standard service rifle of the Swiss Armed Forces.
The SG 552 Commando is fielded in small numbers by certain specialized units and
is known as the Stgw 90 kurz.
United States: Used by some federal agencies, including the Federal Reserve Police.
Vatican City: Used by the Papal Swiss Guard.
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