The SG 550 is an
assault rifle manufactured by
Swiss Arms AG (formerly a division of
Schweizerische Industrie Gesellschaft
SIG Combibloc Group AG, originally founded as ''Schweizerische Industrie Gesellschaft'' (German for Swiss Industrial Company; in French, as ''Société Industrielle Suisse''; and, in Italian, as ''Societa Industriale Svizzera''), and later know ...
, now known as SIG Holding AG) in Switzerland. "SG" is an abbreviation for ''Sturmgewehr'' ("assault rifle"). The rifle is based on the earlier
5.56×45mm NATO SIG SG 540
Sig used as a name may refer to:
*Sig (given name)
* Sig, Algeria, a city on the banks of the Sig River
*Sig Alert, an alert for traffic congestion in California, named after Loyd Sigmon
*Sig River, a river of Algeria also known as Mekerra
sig (l ...
.
History
Development
In 1978, the
Swiss armed forces
The Swiss Armed Forces (german: Schweizer Armee, french: Armée suisse, it, Esercito svizzero, rm, Armada svizra; ) operates on land and in the air, serving as the primary armed forces of Switzerland. Under the country's militia system, re ...
formulated requirements for a successor to the
Stgw 57
The Sturmgewehr 57 is a selective fire battle rifle designed by Schweizerische Industrie Gesellschaft (now SAN Swiss Arms) of Switzerland. It uses a roller-delayed blowback system similar to the H&K G3 and CETME rifles.
The AM 55 entered servic ...
battle rifle
A battle rifle is a service rifle chambered to fire a fully powered cartridge.
The term "battle rifle" is a retronym created largely out of a need to better differentiate the intermediate cartridge, intermediate-powered assault rifles (e.g. the S ...
(known commercially as the SG 510) using the
7.5×55mm GP 11 cartridge
Cartridge may refer to:
Objects
* Cartridge (firearms), a type of modern ammunition
* ROM cartridge, a removable component in an electronic device
* Cartridge (respirator), a type of filter used in respirators
Other uses
* Cartridge (surname), a ...
. Emphasis was placed on
modularity; the weapon family was to include several variants of the base design, including a compact
carbine
A carbine ( or ) is a long gun that has a barrel shortened from its original length. Most modern carbines are rifles that are compact versions of a longer rifle or are rifles chambered for less powerful cartridges.
The smaller size and lighter ...
that would be issued to rear-echelon and support troops, command staff, vehicle crews,
special forces
Special forces and special operations forces (SOF) are military units trained to conduct special operations. NATO has defined special operations as "military activities conducted by specially designated, organized, selected, trained and equip ...
personnel and
paratrooper
A paratrooper is a military parachutist—someone trained to parachute into a military operation, and usually functioning as part of an airborne force. Military parachutists (troops) and parachutes were first used on a large scale during World ...
s. Another aim was to reduce the overall weight of the rifle while retaining comparable or improved accuracy out to 300 m. The solicitation was narrowed down to two designs: the
W+F C42
''Waffenfabrik Bern'' (Weapons Factory Bern), also known as W+F Bern, was an arms manufacturer in Bern, Switzerland, which was a government-owned corporation producing firearms for the Swiss Armed Forces.
List of W+F weapons
*Vetterli rifle
*S ...
(developed by the state-owned
Waffenfabrik Bern
''Waffenfabrik Bern'' (Weapons Factory Bern), also known as W+F Bern, was an arms manufacturer in Bern, Switzerland, which was a government-owned corporation producing firearms for the Swiss Armed Forces.
List of W+F weapons
*Vetterli rifle
*S ...
, using both 6.45×48mm and 5.56×45mm cartridges) and the SG 541 (developed by SIG). In 1981, the experimental
6.45mm GP 80 cartridge was rejected in favor of the more conventional
5.6×45mm Gw Pat 90 round (with a 4.1 g,
tombac
Tombac, or tombak, is a brass alloy with high copper content and 5–20% zinc content. Tin, lead or arsenic may be added for colouration.
It is a cheap malleable alloy mainly used for medals, ornament, decoration and some munitions.
In older u ...
-jacketed,
lead
Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...
core projectile) that is the Swiss equivalent to
NATO
The North Atlantic Treaty Organization (NATO, ; french: Organisation du traité de l'Atlantique nord, ), also called the North Atlantic Alliance, is an intergovernmental military alliance between 30 member states – 28 European and two No ...
's standard 5.56×45mm cartridge.
Production
In February 1983, the decision to adopt the SG 541 was publicly announced (the designation of the rifle was changed in October of the following year to SG 550, while the carbine version became known as the SG 551). Production began in 1986 and four years later the rifle was officially accepted into service in 1990, hence the military designation Stgw 90. Over 600,000 rifles have been delivered since then and production for the military has now ceased.
Design details
Operating mechanism
![Caroline-demontee-p1000529](https://upload.wikimedia.org/wikipedia/commons/6/6e/Caroline-demontee-p1000529.jpg)
The SG 550 is a
selective-fire
Selective fire is the capability of a weapon to be adjusted to fire in semi-automatic, fully automatic, and/or burst mode. The modes are chosen by means of a selector switch, which varies depending on the weapon's design. Some selective-fire we ...
5.56×45mm NATO
assault rifle firing from a
closed bolt
A semi or full-automatic firearm which is said to fire from a closed bolt is one where, when ready to fire, a round is in the chamber and the bolt and working parts are forward. When the trigger is pulled, the firing pin or striker fires the ro ...
. It has a
gas-actuated
Gas-operation is a system of operation used to provide energy to operate locked breech, autoloading firearms. In gas-operation, a portion of high-pressure gas from the cartridge being fired is used to power a mechanism to dispose of the spent ...
piston-driven
long-stroke operating system derived from the
SIG SG 540
Sig used as a name may refer to:
*Sig (given name)
* Sig, Algeria, a city on the banks of the Sig River
*Sig Alert, an alert for traffic congestion in California, named after Loyd Sigmon
*Sig River, a river of Algeria also known as Mekerra
sig (l ...
series of rifles, which uses burnt powder gases vented through a port in the
barrel
A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids, ...
to power the weapon's moving parts. Once inside the gas cylinder, propellant gases pass through an L-shaped channel machined in the piston head and are directed forward towards the gas valve. The pressure build-up in front of the piston head pushes the piston and bolt carrier rearward. As the piston is driven back, the gas port and the L-shaped channel move out of alignment, cutting off the supply of gas to the cylinder. Surplus gas and powder residues are evacuated through an exhaust port in the gas cylinder. The manually adjustable gas valve has two settings, one for normal operation, and the second setting for use in the presence of heavy fouling or icing.
The
rotary bolt locking mechanism consists of two steel locking lugs that engage locking recesses in the breech, and is identical to that used in the SG 540. A spring-loaded
extractor is incorporated into the bolt while a fixed protrusion on one of the receiver's internal guide rails ejects the spent cartridge casings.
Features
![Caroline-pontet-p1000527](https://upload.wikimedia.org/wikipedia/commons/8/88/Caroline-pontet-p1000527.jpg)
The rifle is hammer-fired and has a trigger mechanism with an
ambidextrous
Ambidexterity is the ability to use both the right and left hand equally well. When referring to objects, the term indicates that the object is equally suitable for right-handed and left-handed people. When referring to humans, it indicates that ...
safety
Safety is the state of being "safe", the condition of being protected from harm or other danger. Safety can also refer to risk management, the control of recognized hazards in order to achieve an acceptable level of risk.
Meanings
There are ...
and
fire selector switch that has 4 settings: "S"—safe, "1"—single fire, "3"—3-round
burst
Burst may refer to:
*Burst mode (disambiguation), a mode of operation where events occur in rapid succession
**Burst transmission, a term in telecommunications
**Burst switching, a feature of some packet-switched networks
** Bursting, a signaling m ...
and "20"—fully
automatic fire. The 3-round burst mode "3" and the fully automatic "20" position can be disabled by a rotating safety guard to avert accidentally activating the continuous fire mode. The
trigger
Trigger may refer to:
Notable animals and people
;Mononym
* Trigger (horse), owned by cowboy star Roy Rogers
;Nickname
* Trigger Alpert (1916–2013), American jazz bassist
* "Trigger Mike" Coppola (1900–1966), American gangster
;Surname
* Bru ...
is enclosed in a pivoting trigger guard which can be folded down to the left or right side allowing for unhindered operation with winter gloves. The trigger pull is approximately
The firearm is fed by lightweight 20-round box magazines, 30-, 10- and 5-round magazines are also available. The magazines are
molded
Molding (American English) or moulding (British and Commonwealth English; see spelling differences) is the process of manufacturing by shaping liquid or pliable raw material using a rigid frame called a mold or matrix. This itself may have ...
from a translucent polymer and can be locked together using studs in order to facilitate quicker reloading (
Jungle style). The empty weight of a 20-round magazine is and for a 30-round magazine.
A bolt hold-open device locks the bolt carrier assembly open after expending the last cartridge from the
magazine
A magazine is a periodical publication, generally published on a regular schedule (often weekly or monthly), containing a variety of content. They are generally financed by advertising, purchase price, prepaid subscriptions, or by a combinatio ...
and is released by lifting the bolt catch lever located on the left side of the
receiver. Alternatively, a left-handed shooter may release the bolt by pulling the rubber-coated charging handle to rear a short distance.
The SG 550 has a side-folding skeletonized
buttstock
A gunstock or often simply stock, the back portion of which is also known as a shoulder stock, a buttstock or simply a butt, is a part of a long gun that provides structural support, to which the barrel, action, and firing mechanism are attached ...
(folds to the right side of the receiver) and a
lightweight aluminium bipod
A bipod is a V-shaped portable attachment that helps support and steady a device, usually a weapon such as a long gun or a mortar. The term comes from the Latin prefix ''bi-'' and Greek root ''pod'', meaning "two" and "foot" respectively.
Bipod ...
that folds into grooves in the lower handguard. The hinged stock is firmly locked in the folded position by a socket in the butt which clips into a plastic stud on the handguard; a firm pull will release the stock which is then swung into the closed position and locked by a button catch. A collapsible side-folding stock is also available. The stock,
pistol grip
On a firearm or other tools, a pistol grip is a distinctly protruded handle underneath the main mechanism, to be held by the user's hand at a more vertical (and thus more ergonomic) angle, similar to the how one would hold a conventional pist ...
, and handguards are made of a high-strength
polymer
A polymer (; Greek '' poly-'', "many" + ''-mer'', "part")
is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
, and are produced in either green or black colour options. The
steel
Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant ty ...
receiver housing and several other components are manufactured using stamping and welding; external steel surfaces are finished with a ceramic-reinforced enamel coat known as Ilaflon.
The heavy, cold hammer-forged barrel is screwed into the receiver and is equipped with a slotted "bird cage" type
flash suppressor
A flash suppressor, also known as a flash guard, flash eliminator, flash hider, or flash cone, is a muzzle device attached to the muzzle of a rifle that reduces its visible signature while firing by cooling or dispersing the burning gases that ...
that is also used to launch
rifle grenade
A rifle grenade is a grenade that uses a rifle-based launcher to permit a longer effective range than would be possible if the grenade were thrown by hand.
The practice of projecting grenades with rifle-mounted launchers was first widely used du ...
s (using standard, live
ammunition
Ammunition (informally ammo) is the material fired, scattered, dropped, or detonated from any weapon or weapon system. Ammunition is both expendable weapons (e.g., bombs, missiles, grenades, land mines) and the component parts of other weap ...
) or attach a knife
bayonet
A bayonet (from French ) is a knife, dagger, sword, or spike-shaped weapon designed to fit on the end of the muzzle of a rifle, musket or similar firearm, allowing it to be used as a spear-like weapon.Brayley, Martin, ''Bayonets: An Illustr ...
(the bayonet is supported by a lug located at the base of the gas block). The rifled barrel has 6 right-hand grooves and the Swiss Army specification 254 mm (1:10 in) rifling twist rate is optimized for Swiss military GP 90 ammunition. An export-oriented barrel with a 178 mm (1:7 in) twist rate is also available, designed to stabilize 5.56×45mm NATO rounds with the heavier SS109 and tracer projectiles.
All rifles are
test fired for accuracy and function prior to leaving the factory at the manufacturer's underground 300 m test range. Random new rifles out of production were tested on a machine rest. In a 24 single shot string starting with a cold weapon and using GP 90 ammunition, the R
50 or 50%
windage
Windage is a term used in aerodynamics, firearms ballistics, and automobiles.
Usage
Aerodynamics
Windage is a force created on an object by friction when there is relative movement between air and the object. Windage loss is the reduction in e ...
and
elevation
The elevation of a geographic location is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface (see Geodetic datum § Vert ...
dispersion of any individual weapon must have been within an group at 300 m, the 50% windage and elevation dispersion must have averaged .
The employed
circular error probable
In the military science of ballistics, circular error probable (CEP) (also circular error probability or circle of equal probability) is a measure of a weapon system's precision. It is defined as the radius of a circle, centered on the mean, wh ...
method cannot be converted and is not comparable to US military methods for determining rifle accuracy. When the R
50 results are doubled the hit probability increases to 93.7%.
The gas system's components are made of
stainless steel
Stainless steel is an alloy of iron that is resistant to rusting and corrosion. It contains at least 11% chromium and may contain elements such as carbon, other nonmetals and metals to obtain other desired properties. Stainless steel's corros ...
. The barrel, bolt, bolt carrier, and firing pin are all made with steel that has been
gas nitrided, hardened and tempered. The bolt and carrier, along with most other components internal to the receiver undergo a
phosphating
Phosphate conversion coating is a chemical treatment applied to steel parts that creates a thin adhering layer of iron, zinc, or manganese phosphates, to achieve corrosion resistance, lubrication, or as a foundation for subsequent coatings or p ...
process.
Sights
![Nightsight](https://upload.wikimedia.org/wikipedia/commons/b/b3/Nightsight.JPG)
The SG 550 series rifles have a long sight radius and are equipped with
iron sights
Iron sights are a system of physical alignment markers (usually made of metallic material) used as a sighting device to assist the accurate aiming of ranged weapons (such as a firearm, airgun, crossbow or even compound bow), or less commonly ...
adjustable for both windage and elevation. The sights are similar to those on some
Heckler & Koch
Heckler & Koch GmbH (HK; ) is a German defense manufacturing company that manufactures handguns, rifles, submachine guns, and grenade launchers. The company is located in Oberndorf am Neckar in the German state of Baden-Württemberg, and also ...
weapons, such as the
HK G3
The Heckler & Koch G3 (''Gewehr'' 3) is a 7.62×51mm NATO, selective fire, select-fire battle rifle developed in the 1950s by the German small arms, armament manufacturer Heckler & Koch (H&K) in collaboration with the Spanish state-owned design ...
or
HK MP5
The Heckler & Koch MP5 (german: Maschinenpistole 5) is a 9x19mm Parabellum submachine gun, developed in the 1960s by a team of engineers from the German small arms manufacturer Heckler & Koch. There are over 100 variants and clones of the MP5 ...
. The sights consist of a rear, rotating
diopter
A dioptre (British spelling) or diopter (American spelling) is a unit of measurement with dimension of reciprocal length, equivalent to one reciprocal metre, 1 dioptre = 1 m−1. It is normally used to express the optical power of a lens or cur ...
drum soldered to the receiver and a hooded front post installed in the gas block. The rear sight has an open notch setting marked "1" designed for immediate firing up to 100 m but also contains apertures with settings "2", "3" and "4" corresponding to 200, 300 and 400 m firing ranges. The 400 m setting has a removable iris for sportive shooting. The sights are adjustable via micrometer screws with windage and elevation increments of 0.15
mil (≈0.52
moa
Moa are extinct giant flightless birds native to New Zealand.
The term has also come to be used for chicken in many Polynesian cultures and is found in the names of many chicken recipes, such as
Kale moa and Moa Samoa.
Moa or MOA may also refe ...
), or at 100 m. For night use, the dedicated "1" notch setting in the rear sight drum is provided with two self-luminous
tritium-powered inserts fitted laterally on each side of the notch and additionally in a flip-up post attached to the foresight. When firing rifle grenades the front sight hood is aligned with the uppermost edge of the grenade's warhead, this provides an estimated point of impact up to 75 m. The rifle grenades intended for this purpose were FN/Luchaire Type 58-N bullet-though
anti-tank grenade
An anti-tank grenade is a specialized hand-thrown grenade used to defeat armored targets. Although their inherently short range limits the usefulness of grenades, troops can lie in ambush or maneuver under cover to exploit the limited outward vis ...
s.
![5130 055 Sturmgewehr 90 mit Kern 4x24 Zielfernrohr](https://upload.wikimedia.org/wikipedia/commons/6/68/5130_055_Sturmgewehr_90_mit_Kern_4x24_Zielfernrohr.jpg)
For designated marksman use, the SG 550 is equipped with a Kern 4×24
telescopic sight
A telescopic sight, commonly called a scope informally, is an optical sighting device based on a refracting telescope. It is equipped with some form of a referencing pattern – known as a ''reticle'' – mounted in a focally appropriate po ...
on a quick-detachable mount. The sight weighs and includes a variety of features, such as
STANAG 2324/MIL-STD-1913 compliant mounting components, a
Bullet Drop Compensation (BDC) elevation adjustment knob for ranges from 100 to 600 m, a tritium-illuminated
reticle
A reticle, or reticule also known as a graticule, is a pattern of fine lines or markings built into the eyepiece of an optical device such as a telescopic sight, spotting scope, theodolite, optical microscope or the screen of an oscilloscope, ...
that enables target acquisition in low-light conditions and a diopter eyesight correction adjustment. Included with the sight is a lens hood for mounting on the ocular that reduces image quality-impairing stray light and a gray filter for glare reduction. The basic model of this optical sight was already used on the Stgw 57.
The upper receiver can accept quick-detachable
rails
Rail or rails may refer to:
Rail transport
*Rail transport and related matters
*Rail (rail transport) or railway lines, the running surface of a railway
Arts and media Film
* ''Rails'' (film), a 1929 Italian film by Mario Camerini
* ''Rail'' ( ...
and adapters used to mount optics (STANAG 2324 compliant). The
scope mounting system consists of a centering hole located on the front face of the rear sight assembly and a
dovetail-like mounting point at the front end of the receiver. Swiss Arms (respectively
Brügger & Thomet
B&T AG (formerly Brügger & Thomet AG; sometimes rendered B+T) is a Swiss defence supplier specializing in the design and manufacturing of firearms and tactical components such as sound suppressors and rail systems. The company is based in Thun, ...
) offer several types of quick-release scope mounts and
Picatinny rail
The Picatinny rail ( or ), or Pic rail for short, also known as a MIL-STD-1913 rail, 1913 rail or STANAG 2324 rail (cancelled), is a military standard rail interface system that provides a mounting platform for firearm accessories. It was o ...
s. A version of the rifle with an integral receiver-mounted Picatinny rail is also offered; in this configuration the weapon is fitted with flip-up emergency battle sights—a rear aperture sight which folds down into a recess in the rail and a folding front blade.
Accessories
![Bayonet SG550](https://upload.wikimedia.org/wikipedia/commons/4/45/Bayonet_SG550.JPG)
Both the rifle and carbine come standard with a spare magazine,
sling,
cleaning
Cleaning is the process of removing unwanted substances, such as dirt, infectious agents, and other impurities, from an object or environment. Cleaning is often performed for aesthetic, hygienic, functional, environmental, or safety purposes. Cl ...
kit and a loading aid for rapid magazine filling.
The full-sized SG 550/551 will accept SIG's
40 mm
40 mm grenade (also styled 40mm grenade) is a generic class-name for grenade launcher ammunition ( subsonic shells) in caliber. The generic name stems from the fact that several countries have developed or adopted grenade launchers in ...
GL 5040/5140 grenade launcher
A grenade launcher is a weapon that fires a specially-designed large-caliber projectile, often with an explosive, smoke or gas warhead. Today, the term generally refers to a class of dedicated firearms firing unitary grenade cartridges. The mos ...
(Swiss military designation: 40 mm ''Gewehraufsatz'' 97), which is mounted under the barrel via an eccentric latch and replaces the lower
handguard
A barrel shroud is an external covering that envelops (either partially or full-length) the barrel of a firearm, to prevent unwanted direct contact with the barrel (e.g. accidental collision with surrounding objects, or the user accidentally tou ...
. The grenade launcher is a
single-shot
Single-shot firearms are firearms that hold only a single round of ammunition, and must be reloaded manually after every shot. The history of firearms began with single-shot designs, then multi-barreled designs appeared, and eventually many ce ...
breech-loaded weapon that is supplied with a leaf sight that attaches to the rifle's rear sight base and enables accurate firing out to 200 m. The lightweight
aluminium
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...
launcher weighs unloaded, and is operated independently of the rifle. It can use a wide array of 40×46mm grenades, including extended range high-pressure types and non-lethal baton or anti-riot projectiles. The compact SG 552/553 can be fitted with smaller GL 5340 underbarrel grenade launcher.
An Stgw 90
bayonet
A bayonet (from French ) is a knife, dagger, sword, or spike-shaped weapon designed to fit on the end of the muzzle of a rifle, musket or similar firearm, allowing it to be used as a spear-like weapon.Brayley, Martin, ''Bayonets: An Illustr ...
can also be mounted to the rifle. The bayonet has an overall length of 310 mm and a muzzle ring diameter of 22 mm. The 177 mm long blade is single-edged and it has no
fuller. The bayonets are manufactured exclusively for the Swiss Army by
Victorinox
Victorinox () is a knife manufacturer and watchmaker based in the town of Ibach, in the Canton of Schwyz, Switzerland. It is well known for its Swiss Army knives. The Swiss Army knives made by Victorinox are made of a proprietary blend stee ...
and in the past by
Wenger
Wenger was a Swiss cutlery manufacturer that exists today as a line of once rival Victorinox, and a brand name for watches and licensed products owned by it. Founded in 1893, it was best known as one of two companies to manufacture Swiss Arm ...
until Victorinox acquired Wenger in 2005. With a proper lug adaptor, the rifle will also accept a NATO-pattern KCB-77 (made originally by Carl Eickhorn of
Solingen
Solingen (; li, Solich) is a city in North Rhine-Westphalia, Germany. It is located some 25 km east of Düsseldorf along the northern edge of the region called Bergisches Land, south of the Ruhr area, and, with a 2009 population of 161,366, ...
,
West Germany
West Germany is the colloquial term used to indicate the Federal Republic of Germany (FRG; german: Bundesrepublik Deutschland , BRD) between its formation on 23 May 1949 and the German reunification through the accession of East Germany on 3 O ...
) or the American
M9.
Variants
SG 551
![SIG-551-p1030048](https://upload.wikimedia.org/wikipedia/commons/0/0f/SIG-551-p1030048.jpg)
The SG 551 carbine has a short pattern barrel, gas tube and piston compared to the SG 550. The SG 551 series rifles have a 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:
* SG 551-1P police carbine, designed to engage point targets out to 300 m; equipped with a Hensoldt 6x42 BL
telescopic sight
A telescopic sight, commonly called a scope informally, is an optical sighting device based on a refracting telescope. It is equipped with some form of a referencing pattern – known as a ''reticle'' – mounted in a focally appropriate po ...
and detachable cheek riser.
* 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.
* SG 551 LB carbine with an extended barrel that enables the use of rifle grenades and a bayonet.
SG 552 Commando
![Stgw 90 kurz](https://upload.wikimedia.org/wikipedia/commons/8/8a/Stgw_90_kurz.jpg)
The compact SG 552 Commando (full designation as the 552-2P) carbine was released in July 1998. It has a shorter 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 SG 552 series rifles have a long sight radius. 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
The AK-47, officially known as the ''Avtomat Kalashnikova'' (; also known as the Kalashnikov or just AK), is a gas operated, gas-operated assault rifle that is chambered for the 7.62×39mm cartridge. Developed in the Soviet Union by Russian s ...
: 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 barrel with provision to fire rifle grenades and support a bayonet. The SG 552 models were discontinued in 2008 and replaced by the SG 553. Upgrade part kits are available to convert a SG 552 in to a SG 553.
SG 553
![SIG SG 553 LB](https://upload.wikimedia.org/wikipedia/commons/6/61/SIG_SG_553_LB.jpg)
The SG 553 is an improved version of the SG 552 and was released in 2008. Even though it mostly resembles the SG 552, the SG 553 has one key advantage, the recoil spring is now wrapped around the piston rod as in the SG 550/551 models, which address several reliability issues encountered in the SG 552 and also allows the usage of the standard SG 550/551 charging handle. The SG 553 series rifles have a long sight radius. A long barrel version of the SG 553 known as the SG 553 LB incorporates a barrel with provision to fire rifle grenades and support a bayonet. Further factory options for the SG 553 rifle series are an integrated receiver
Picatinny rail
The Picatinny rail ( or ), or Pic rail for short, also known as a MIL-STD-1913 rail, 1913 rail or STANAG 2324 rail (cancelled), is a military standard rail interface system that provides a mounting platform for firearm accessories. It was o ...
and an adjustable butt stock. The SG 553 R is a variant chambered for the
7.62×39mm
The 7.62×39mm (aka 7.62 Soviet, formerly .30 Russian Short) round is a rimless bottlenecked intermediate cartridge of Soviet origin. The cartridge is widely used due to the worldwide proliferation of Russian SKS and AK-47 pattern rifles, as ...
cartridge fed from
AK family box magazines. There is also a
.300 AAC Blackout
The .300 AAC Blackout (designated as the 300 BLK by the SAAMI and 300 AAC Blackout by the C.I.P. or 300 AAC Blackout'' C.I.P. TDCC sheet 300 ACC Blackout/ref>), also known as 7.62×35mm, is an intermediate cartridge developed in the United Sta ...
variant of the SG 553 known as the SG 553 BK which was first shown at
IWA OutdoorClassics
IWA OutdoorClassics, also referred to as simply IWA, short for ''Internationale Waffen Ausstellung'' (International Weapons Exhibition), is an annual trade fair held in the Messezentrum Nuremberg in Bavaria, Germany for the hunting, shooting spor ...
in 2016.
SG 552-A1
The SG 552-A1 is a SG 552 rifle that has been modified to function like the SG 553. The modifications are available as a conversion kit that includes a new bolt carrier, charging handle, recoil spring and gas tube.
SG 550-1 Sniper
Another member of the SG 550 family is the SG 550-1 Sniper variant designed at the request of the Swiss Police. Introduced in 1988, This accurized rifle has a refined two-stage trigger (the pull force was reduced from to , a heavy, hammer-forged long barrel with a 254 mm (1:10 in) rifling twist rate (it has no flash hider) and is used exclusively with telescopic sights. The new folding stock has an adjustable cheek piece and a spacer system on the butt, the ergonomic pistol grip's angle of inclination can be regulated, the forend was shortened, and the bipod features a height and cant adjustment mechanism. This model is no longer in production.
Civilian variants
The SG 550/551/552/553 are also available in
semi-automatic only configurations, intended for the civilian shooting market. Among these variants are the SG 550/551/552 SP, PE 90 and SIG Sport rifles. The SG 550 series is available with either 178 mm or 254 mm (1:7 and 1:10 in)
twist rate
In firearms, rifling is machining helical grooves into the internal (bore) surface of a gun's barrel for the purpose of exerting torque and thus imparting a spin to a projectile around its longitudinal axis during shooting to stabilize the pro ...
barrels. Rifles designated SG 55x-1 have a 254 mm (1:10 in) twist rate, while models marked SG 55x-2 have a 178 mm (1:7 in) twist rate. The ordinance GP 90 ammunition is optimized for use with the original Swiss 254 mm (1:10 in) rifling twist rate.
![Sig 556 Classic](https://upload.wikimedia.org/wikipedia/commons/1/12/Sig_556_Classic.jpg)
Due to import restrictions, the American civilian market required a partially American-made version assembled by
SIG SAUER, Inc. in
Exeter, New Hampshire
Exeter is a town in Rockingham County, New Hampshire, United States. The population was 16,049 at the 2020 census, up from 14,306 at the 2010 census. Exeter was the county seat until 1997, when county offices were moved to neighboring Brentwood. ...
. The SIG556 is designed to meet these requirements. The 556 lacks full-auto capability and the overall length is . One difference is a new
aluminum
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has ...
lower receiver that accepts
M16 STANAG magazines and an
M4 telescoping buttstock. The barrel's twist rate is 178 mm (1:7 in).
There are many variants of this rifle offered for sale. The first variant was sold with an aluminum Picatinny rail on the upper receiver and a series of plastic rails on the handguard. The market pushed SIG to produce the rifle with the slimmer profile 551-type handguards and a hooded front sight; this version is marketed as the SIG556 Classic. Several folding stock models have been released as well as variants with railed forend combinations. Another variant is the SIG 556 DMR featuring a barrel. SIG P556 pistol variants with 10-inch barrels are also available. In 2012 the SIG 556 R or SIG 556 Russian chambered for the
7.62×39mm
The 7.62×39mm (aka 7.62 Soviet, formerly .30 Russian Short) round is a rimless bottlenecked intermediate cartridge of Soviet origin. The cartridge is widely used due to the worldwide proliferation of Russian SKS and AK-47 pattern rifles, as ...
cartridge and using
AK-pattern box magazines was introduced. The first generation of SIG556R rifles had a number of performance issues that were later resolved in later production runs of the SIG556R.
In January 2014, SIG introduced the 556xi series rifles as an improvement to the 556 and 556R series rifles.
As of May 2017, SIG has discontinued the SIG556, SIG556R, and 556xi series of rifles and no longer displays those models on the products section of their website.
The
SIG 522LR
The SIG Sauer 522 LR is a .22 LR semi-automatic, blowback operated rifle. It is patterned after the SIG 55x series rifles that fire 5.56x45mm centerfire cartridges. The 522 fires .22 LR ammunition and serves as a training rifle for its larger ...
is a
.22 .22 caliber, or 5.6 mm caliber, refers to a common firearms bore diameter of 0.22 inch (5.6 mm).
Cartridges in this caliber include the very widely used .22 Long Rifle and .223 Remington / 5.56×45mm NATO.
.22 inch is also a popular ...
-caliber sporting rifle styled after the SG 551. It uses a simple
blowback semi-automatic operating system and its barrel has a 406 mm (1:16 in) twist rate. Due to its operating principle, the rifle has no mechanical commonality with other SG 550 variants. The SIG522 accepts commonly available AR-style .22-caliber conversion magazines.
In the U.S, a variety of semi-automatic SwissArms firearms are available for sale. Due to U.S. import regulations, they are imported as a pistol.
Regulation in Canada
On 27 February 2014, the Canadian semi-automatic "Classic Green" sporting rifle, also known as the ''Swiss Arms PE 90'', was re-classified as a "prohibited weapon". The rifle had been popular with hunters and gun enthusiasts, who until February 2014, only required a
possession and acquisition licence to obtain the rifle. However, late in 2013, a gun dealer had imported some PE 90 rifles from Switzerland and brought them to Canada for sale. After some were sold, it was alleged that the rifles in question were of a variant not allowed in Canada (PE90). Upon investigation and examination by the RCMP, this was proven inconclusive, however, the RCMP went further and decided the versions in Canada were too close to the PE90 and reclassified the rifles and declared the entire model line prohibited, with possible confiscation for destruction. This caused outrage amongst owners and lobbyists, who felt that the RCMP exceeded their authority, and that such policy changes should be enacted by legislation. The
National Firearms Association
The National Firearms Association (NFA; french: Association Nationale des Armes à Feu) is a Canadian non-profit association based in Edmonton. Its main goals are the repeal and replacement of the Firearms Act (Bill C-68), which was introduced i ...
of Canada considered pursuit of the matter through the legal system. On 31 July 2015, the Canadian government overturned the reclassification and returned the Swiss rifles to the original classifications. On 1 May 2020, in the wake of the
Nova Scotia attacks, the rifles were again reclassified as Prohibited Firearms via Order in Council.
Accuracy potential
The following tables list accuracy statistics for typical in service Stgw 90 rifles firing Swiss 5,6 mm Gw Pat 90 service ammunition obtained by firing from the bipod. The statistics were computed under the 1990s Swiss method for determining accuracy, which is more complex than Western methods which usually involve firing a group of shots and then measuring the overall diameter of the group. The Swiss method differs in that after a group of shots is fired into the target from a machine rest hits on the outer part of the target are disregarded, while only half of the hits on the inner part of the circles are counted (50% or R
50), which significantly reduces the overall diameter of the groups. The vertical and horizontal measurements of the reduced groups are then used to measure accuracy. This
circular error probable
In the military science of ballistics, circular error probable (CEP) (also circular error probability or circle of equal probability) is a measure of a weapon system's precision. It is defined as the radius of a circle, centered on the mean, wh ...
method used by the Swiss and other European militaries cannot be converted and is not comparable to US military methods for determining rifle accuracy. When the R
50 results are doubled the hit probability increases to 93.7%.
![Circular error probable - example](https://upload.wikimedia.org/wikipedia/commons/4/4b/Circular_error_probable_-_example.png)
*
R50 means the closest 50 percent of the shot group will all be within a circle of the mentioned diameter.
*
R93.7 means the closest 93.7 percent of the shot group will all be within a circle of the mentioned diameter.
*
For rapid single shot series (5 rounds quickly fired within 2.5 to 5 seconds) the dispersion doubles compared to single shot fire.
*
In 3-round burst mode and fully automatic firing mode the dispersion quadruples compared to single shot fire.
For reference a 1
minute of arc
A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...
(MOA) circle at has a diameter of . The radius of a circle is half its diameter.
Acceptance accuracy requirements
The R
50 dispersion of × from the above table was also the accuracy standard any Stgw 90 had to pass, firing a 24-round group of a machine rest. During production the Swiss military additionally demanded for acceptance at random selected new Stgw 90 weapons out of a production batch, firing a 24-round group with Swiss 5,6 mm Gw Pat 90 service ammunition of a machine rest at a range of , the R
50 horizontal and vertical dispersion had to average × . Any result from an individual as such tested weapon, was not allowed to exceed a maximal R
50 dispersion of × .
Gallery
Image:Caroline-profile-bipode-p1000509.jpg, With bipod extended.
Image:Fass90-bayonette-p1000786.jpg, With bayonet
A bayonet (from French ) is a knife, dagger, sword, or spike-shaped weapon designed to fit on the end of the muzzle of a rifle, musket or similar firearm, allowing it to be used as a spear-like weapon.Brayley, Martin, ''Bayonets: An Illustr ...
.
Image:Caroline-crosse-repliee-p1000515.jpg, Stock folded.
Image:Caroline-canon-degivrage-p1000523.jpg, Flash suppressor and gas regulator.
Image:SIG 550 IMG 3276.jpg, The gas block integrates an adjustable gas regulator, the front sight with a flip-up night sight post, and the bayonet lug on the flash suppressor.
Image:SIG-552-p1030040.jpg, The SG 552 Commando version with integral Picatinny rail
The Picatinny rail ( or ), or Pic rail for short, also known as a MIL-STD-1913 rail, 1913 rail or STANAG 2324 rail (cancelled), is a military standard rail interface system that provides a mounting platform for firearm accessories. It was o ...
and accessories.
Users
See also
*
SIG SG 530
*
SIG SG 540
Sig used as a name may refer to:
*Sig (given name)
* Sig, Algeria, a city on the banks of the Sig River
*Sig Alert, an alert for traffic congestion in California, named after Loyd Sigmon
*Sig River, a river of Algeria also known as Mekerra
sig (l ...
*
SIG Sauer SIG516
The SIG Sauer SIG516 is a semi-automatic rifle manufactured by SIG Sauer. It is an AR-15 style rifle chambered in 5.56×45mm NATO. Introduced in 2010, the SIG516 was discontinued as of 2019. A variant chambered in 7.62x51mm NATO, the SIG716i, re ...
*
Gun politics in Switzerland
Firearms regulation in Switzerland allows the acquisition of semi-automatic, and – with a may-issue permit – fully automatic firearms, by Swiss citizens and foreigners with or without permanent residence.The law of 1997 (SR 514.54) made ...
*
List of assault rifles
An assault rifle is a rifle that uses an intermediate cartridge, a detachable magazine, and can switch between semi-automatic/fully automatic fire. Assault rifles are currently the standard service rifles in most modern armies. Some rifles listed ...
*
List of carbines
A ''list'' is any set of items in a row. List or lists may also refer to:
People
* List (surname)
Organizations
* List College, an undergraduate division of the Jewish Theological Seminary of America
* SC Germania List, German rugby union ...
*
List of sniper rifles
This article is a listing of major precision rifle variants used by snipers from around the world.
A hunting or precision rifle equipped with a telescopic optic has been long described as a sniper rifle. Below is the list of precision rifles us ...
References
Bibliography
*''Règlement 53.96 Fusil d'assaut 5,6 mm 1990''
External links
Swiss Arms PE 90 brochureBiggerhammer.net—portal for articles, information and manuals, etc. on the SIG Stgw 57/SG 510/AMT and SG 550 rifle seriesSG 550/551 technical data and test documentationThe SIG SG 550 series—information, manuals and linksSG 550/551 instruction manualSG 552 instruction manualSwiss Armed Forces Stgw 90 manual The Guns of Venezuela
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Weapons and ammunition introduced in 1986
5.56 mm assault rifles
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Assault rifles of Switzerland
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