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The SIG SG 550 Series

  SIG SG 550

Image courtesy of the Gunnery Network

There is an old saying, "Switzerland doesn't have an army, it is an army."   Nearly every eligible Swiss Male serves in the Swiss Army as a regular, or reservist until he is 40.  Each one of these soldiers is issued a rifle and two sealed boxes of ammo to take home with him.  The goal: complete mobilization of Switzerland with 48 hours.  Indeed many feel, complete mobilization can occur with one afternoon.

The Swiss take their independence very seriously and believe the key to maintaining their independence is making the prospect of invading Switzerland so horrific that none will attempt it.  Close observation of the Swiss countryside, will reveal mined bridges, hidden artillery, bomb shelters, and carefully prepared kill zones.  In addition, patrols of Swiss Rifleman scour the countryside, familiarizing themselves with every inch of the land, they hope they never have to defend.

The Swiss Rifleman has always been well armed.  The Model 1869 Swiss Vetterli was the first repeating rifle to be adopted by any army as it's standard round.  The Schmidt-Rubin series of rifles are some of the most accurate standard issue military rifles ever produced.  Similarly, Stgw.57 is perhaps the most accurate battle-rifle ever produced.  Combined with the accuracy of the rifles, Switzerland is a nation of shooter.  Annual shooting contest attract over 200,00 competitors.  All of whom shoot at target 300 meters away.

It was partially due to the enjoyment of long range shooting the slowed the replacement of the GP11 7.5x55 cartridge with a more modern 5 mm round.  Earlier 5.56 NATO round were shorter range rounds, and not especially accurate out to 300m.  Yet, NATOs adoption of the SS109 cartridge, with it's heavier barrel and longer range, finally cleared the way for the Swiss to announce the adoption  the 5.6 GP90 round (functionally identical to the SS109 round) in 1983.

The SIG SG 530/1

Overall Length : 37.5 inches
Barrel Length: 15.4
Weight (empty): 7.2 lbs
Cyclic ROF: 600 rpm
Capacity: 30rd detachable box magazine
Muzzle Velocity: 2850 fps

Schweizerische Industrie-Gesellschaft (SIG) was no stranger to the 5.56 round.  In the late 60s,  SIG began work  to develop a lightweight rifle chambered for the 5.56 round.  The SIG SG 530 was something of a hybrid rifle.  It retained the roller locks of the SIG 510 series, yet added gas cylinder.  The adoption of the gas cylinder was intended to prevent the rifle from cooking off it's ammo (Cook-off is a condition where the chamber of the rifle is hot enough to ignite a cartridge.)

The SIG 530 was well made, but expensive.  It failed to attract any customers, and soon the project was shelved in favor of the SIG SG 540

The SIG SG 540

Picture from Small Arms Profile

Overall Length : 37.4 inches
Barrel Length: 18.1
Weight (empty): 7.2 lbs
Cyclic ROF: 650-800 rpm
Capacity: 20 or 30rd detachable box magazine
Muzzle Velocity: 3215 fps

The SIG SG 540 dispensed with the complex roller lock action, and instead used the simpler, yet robust rotating bolt action made famous by the AK series of rifles.  However, the gas system was improved by adding an adjustable gas regulator.  Other production shortcuts, such as stampings and casting were employed to further reduce the cost of the rifle.  The SG 540 could be equipped to fire either in full auto mode, or three shot burst.  However, converting between the two required switching out  certain fire control components.  The SG 540 also featured a folding bipod, H&K style drum rear sight, and the ability to use a wide variety of accessories such as telescopic sights and  bayonets.

The SG 540 was a moderate success.  It was manufactured under license by the French company Manurhin for the French army.  In addition, SG 540s have been to to 17 other armies throughout the world.

In 1979, SIG produced a modified SIG 540 for weapon trials.  The rifle, designated the SG 541, was produced in two barrel lengths, was equipped with a synthetic skeleton buttstock, possessed an integral bipod, and a modified selector/safety switch.  In 1983, the SG 541 was adopted by the Swiss Government to replace the Stgw.57.  However, funding difficulties delayed the final acceptance.

A carbine version, the SG 543 was also produced.  As was the SG 542, which was chambered for the 7.62 NATO round.

A SIG SG 550 (top) & SIG SG 551 (bottom)

Image courtesy of the Gunnery Network
  SG 550 SG 551 SG 552 
Overall Length : 39.3" 32.5" 28.7"
Barrel Length: 20.8" 16.0" 8.9"
Weight 9.04lbs
(w/empty magazine & bipod)
(w/empty magazine)
(w/empty magazine)
Cyclic ROF 700rpm 700rpm 700rpm
Capacity 5,20 or 30rd detachable box magazine 5, 20 or 30rd detachable box magazine 5, 20 or 30rd detachable box magazine
Muzzle Velocity: 3215 fps 3000 fps  2379fps

Stg.90 Left Receiver close-up

Images courtesy of Biggerhammer.net

By 1984, the SG 541 had evolved into the SG 550.  The previously optional three round burst feature, was now incorporated into the fire control mechanism, which now allowed, single, three-round burst, and full automatic capability.  In addition, the gas system was improved and the folding buttstock now incorporated the distinctive void.  Adopted by the Swiss Army in 1984, the SG 550 was redesigned as the Stg.90 (Sturmgewehre 90.)  An initial order for 600,000 Stg.90s was made, and the first deliveries began in 1986.

Stg.90 Bolt & Carrier

Images courtesy of Biggerhammer.net

The Stg.90 is certainly a feature laden rifle.  It incorporates a fire control system with an ambidextrous selector switch and is capable of firing single shots, three round bursts, and fully automatic fire.  It possesses flip up tritium glow-in-the-dark night sights. The sights are mounted low, allowing the shooter to hold his head lower when aiming the rifle, thus affording greater cover against return fire.  In addition, the Stg.90 also has provision for mounting a wide variety of scope and optical sights.

Front Sight 
w/flip up night sight.
Adjustable Drum Rear sight
Images courtesy of the Gunnery Network

The Stg.90s folding stock tends to be rigid and easy to operate.  Nor is the rifles balance effected by having the stock folded.  The buttplate has a rubber pad to firmly seat the rifle on the shoulder.  The pistol grip is hollow, to allow the carrying of a cleaning kit.  The magazines are transparent, allowing for easy checking of ammunition, and the magazines can be clipped together for convenience of carry.  The forearm accepts the mounting of a 40mm Grenade Launcher. The Stg.90 is also equipped with an integral bipod.

Stg.90 Magazine

Images courtesy of Biggerhammer.net

The Stg.90 is well suited the service in Switzerland.  The  trigger guard folds to the side, to allow firing by mitten wearing soldiers.  In addition the internal of the rifle are well shielded against elements.  During the trials the Swiss subjected the Stg.90 to rain, sand, dust, and temperature trials.  The Stg.90 met all these trial to the satisfaction of the Swiss.  For more details click here.  It has been reported that some of the early production Stg.90 had problems with corrosion of the gas tubes, but that problem appears to have been resolved.

The SIG SG 551

In addition to a standard length rifle, the Swiss also required a shortened rifle for the use of the "Headquarters Staff."   The SIG 551 is mechanically identical to the Stg.90, except for it's shorter length and omission of the bayonet.  A variation, the SIG SG 551-1P, was specifically designed for Law Enforcement use, and comes equipped with a Hensholt 6x42 scope.  A second variation the SG 550-LB  mounts a slightly longer flash-hider and is capable of firing Grenades.

The SIG SG 552

Images courtesy of the Gunnery Network

The SIG SG 552 Commando is a still shorter variation of the SG 550 series.  The SG 552 has a 8.9 inch barrel, and utilizes a different flash suppresser.


Images courtesy of the Gunnery Network

Overall Length : 44.5 inches
Barrel Length: 26
Weight (empty): 15.48 lbs
Cyclic ROF: n/a
Capacity: 5, 20, or 30rd detachable box magazine
Muzzle Velocity: ~3215 fps

Designed specifically for Law Enforcement units, the SG 550 Sniper model uses many of the Stg.90s basic components, but also incorporates numerous improvements.  Most notably, the 26 inch heavy barrel.  Also,  the bipod, the buttstock and pistol grip are all highly adjustable.  The SG 550 Sniper Rifle lacks the selective fire capability of the Stg.90, but is equipped with a refined two stage trigger.  Also, the SG 550 Sniper Rifle lacks fixed sights, but is equipped a removable scope mount.

The Stg.90 Bayonet

The Stg.90 is quite an accurate rifle.   At Swiss Shooting Festivals, the Stg.90 has largely supplanted many of the older models, and is quite competitive at 300 meters.  Indeed, according to the SIG Swiss web site, over 30,000 Swiss Shooters have purchased the Stg.90 as their own personal target rifle.  From a nation of shooters, that is truly high praise.

The production run for the STG.90 appears to be nearing it's end.  According to Andrea Schellmoser Sales Assistant for SIGARMS... 

"Regarding information on rifles produced by SIG for the Swiss Military
kindly be informed that we, SIG Arms AG, Neuhausen Switzerland had a
contract with the Swiss Army and have delivered 1.1 Mio. rifles in 45 years
to them.
This said contract has this year run out and the last batch of rifle will be
delivered soon.

We hope to have been of service with this information.

Best regards

SIG Arms AG"

It will be curious to see what the future holds for Swiss Rifles.

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