Weapons expertise STGW 90 / SG 550

Weapons expertise: Assault rifle 90 / SG 550

**Alt-Text:** "Swiss assault rifle 90 (SIG 550) in side view - modern, precise and robust ordnance rifle with folding stock and 5.6mm calibre."

The Assault rifle 90 (Stgw 90) is the standard weapon of the Swiss Army and is also used Shooting off duty widely used. Thanks to its high precision, robust construction and versatile application possibilities it is appreciated by marksmen, young marksmen and security forces.

This article provides comprehensive knowledge about the Stgw 90 - from Technical data and functionality about the Correct handling and safety rules up to the Maintenance and care.

1. technical data and properties

The Stgw 90 is a 5.6 mm calibre riflewhich has a Pressurised gas charging system with twist lock works. It is specially designed for the precise single fire mode optimised and offers high targeting accuracy.

Technical specifications:

Assault rifle 90 / SG 550 specifications

Feature	Value
Total length	1000 mm (folded: 772 mm)
Barrel length	528 mm
Weight	4.345 kg (with full magazine)
Magazine capacity	20 cartridges
Types of fire	Single fire, 3-shot automatic
Muzzle velocity	905 m/s

👉 Important: In off-duty shooting, only Single fire and rapid fire allowed!

2. the main components of the Stgw 90

Components of the 5.6 mm assault rifle 90 (SIG SG 550) - barrel, front sight attachment, hand guard, bolt housing, rear sight, butt, pistol grip, trigger housing, magazine, carrying strap and bipod support.

Components of the 5.6 mm Stgw 90
1 run
2 Grain attachment
3 Hand protection
4 Shutter housing
5 Dioptre sight
6 Pistons
7 Pistol grip
8 Trigger housing
9 Magazine
10 carrying straps
11 Bipod support

The Sturmgewehr 90 consists of several important components that are crucial to its functionality:

1st barrel and muzzle brake

The barrel is equipped with a Muzzle brake which reduces recoil and improves stability.

Barrel of the assault rifle 90 (SIG SG 550) with fixed front sight attachment, screwed to the bolt housing and equipped with a flash hider at the muzzle.

Run
1 Shutter housing
2 Run
3 Grain attachment
4 fire silencers
5 Bayonet lock

2. bolt housing and rear sight

The Diopter sight offers a Precise target acquisition. In addition, a Telescopic sight be mounted.

Bolt housing of the assault rifle 90 (SIG SG 550), firmly screwed to the barrel, including front sight attachment for precise target acquisition.

Shutter housing
1 rear sight with rear scope mount
2 Sealing lip
3 Charging handle lock
4 locking carriers
5 Charging handle
6 Front scope holder
7 Shutter housing

3. magazine

The Stgw 90 uses a Transparent plastic magazine with a capacity of 20 cartridges. This means that the fill level is visible at all times.

Magazine of the assault rifle 90 (SIG SG 550) with magazine box, magazine spring, feeder, coupling buttons and magazine base for safe cartridge feed.

Magazine
1 Magazine assembled
2 coupling knobs
3 Bearing
4 Magazine box
5 Magazine base
6 Magazine base holder
7 Magazine spring
8 Feeder

4. trigger device and safety catch

The fuse switches are located on both sides of the housing and allow a Fast operation.

Trigger mechanism of the assault rifle 90 (SIG SG 550) with bolt catch, serial fire lock, safety lever, trigger, swivelling trigger guard, magazine catch and pistol grip.

Trigger device
1 fastener holder
2 Series fire lock
3 Rear trigger housing bolt
4 safety lever
5 Pistol grip
6 Cover for pistol grip
7 Deduction
8 Swivelling trigger guard
9 Magazine holder

5. folding piston

The Piston can be folded for transport or use in confined spaces.

Folded butt of the assault rifle 90 (SIG SG 550) with butt safety, clip, butt cap and eyelet for the sling.

Piston folded down
1 Piston fuse
2 clips
3 Piston cap
4 Eyelet for carrying strap

3. safety rules for handling the assault rifle 90

Safe handling of the Stgw 90 requires full concentration and a sense of responsibility at all times. Any negligence can have serious consequences. Therefore, the following four basic rules apply, which must be observed under all circumstances:

Safety rules for weapons

1️⃣ All weapons must always be considered loaded! Regardless of whether the firearm is actually loaded or not, it must always be treated as such. An unintentional shot can only be prevented if you are aware of this rule at all times.

2️⃣ Never aim at something you don't want to hit! The muzzle of the firearm must never be pointed at people, animals or objects that are not intended to be shot at. This also applies if the gun is believed to be locked or unloaded.

3️⃣ Finger always remains outside the trigger guard until you want to shoot! The finger may only be placed on the trigger when you are sure that a shot is to be fired. This prevents unintentional firing, especially in stressful situations.

4️⃣ Be sure of your goal - the background counts too! Before pulling the trigger, you need to be aware not only of the target, but also of the entire area behind and next to it. Bullets can penetrate or ricochet and cause unintentional damage or injury.

Why are these rules vital?

These four principles are globally recognised safety rules and apply to any form of firearm use. They save lives and prevent accidents. Everyone who carries a weapon bears a great responsibility. Discipline, vigilance and respect for the weapon are essential.

💡 Note: Safety always comes first - there are no exceptions!

Loading and unloading the Stgw 90:

Secure weapon (fuse set to "S")
Insert magazine
Pull back the bolt and check the cartridge feed
To fire, release the safety (safety to "1") and aim

To the Unloading the magazine is removed and the chamber with the Through-loading movement checked.

4. shooting practice with the Stgw 90

The Stgw 90 offers a Excellent shooting performance - but only if the shooter Correct posture and technique used.

Firing positions

Laid flat: Maximum precision thanks to stable hold
Standing freehand: More difficult, but essential for competitions
Kneeling: A mixture of stability and mobility

Aiming technique and sighting

The Diopter sight of the Stgw 90 Precise aiming. The decisive factors are:
✅ The right Eye position
✅ A stable Stop
✅ Control over Breathing and trigger technique

Targets

At the Targets the grain is precisely Target centre in Agreement brought - this is called "Aim spot". This principle applies to all Distances and targets (e.g. combined target A or field target B).

📌 Important points when aiming:

✅ The eye cannot see the front sight, rear sight and target at the same time. Therefore, the focus should always be on the Grain The sight and target appear slightly out of focus.
✅ Keeping both eyes open can be unfamiliar at first, but reduces fatigue quickly and improves perception when shooting.

With a little practice, this technique becomes Natural target detection and leads to more precise shots.

Aiming pattern 'spot' on the combined target A - front sight and target centre in line for precise aiming with the assault rifle 90. — Target image "Stain" Combined **Disc A**

Target pattern 'spot' on the combined target B - front sight and target centre in line for precise aiming with the assault rifle 90. — *Target image "Stain" Combined* *Disc* B

Correct

To correct the height or side, turn the corresponding correction screw. Turning the correction screws by one grid position shifts the point of impact by approx. 0.15 ‰.

Illustration of a visor with numbered labelling. The labelled components are: (1) bolt housing, (2) elevation correction screw, (3) sight drum and (4) side correction screw.

Height correction:
For low shots, the elevation correction screw is turned clockwise;
for high shot analogue counterclockwise.

Elevation correction firing pattern Stgw 90 — *Correction symbol on the visor (height correction)*

Height correction screw on the STGW 90 / SIG SG 550 for precise adjustment of the sight height for exact shot corrections at various distances.

Height correction screw
1 Correction symbol Target centre
2 Correction symbol firing position
3 Direction of rotation of the correction screw

Correction page:
When firing to the right, the side correction screw is turned anti-clockwise;
with left-hand shot analogue clockwise.

Side correction firing pattern Stgw 90 — *Correction symbol on the visor (side correction)*

Side correction screw on the STGW 90 / SIG SG 550 for fine adjustment of the sights for precise horizontal shot corrections.

Lateral correction screw
1 Correction symbol Target centre
2 Correction symbol firing position
3 Direction of rotation of the correction screw

Meeting point shift per detent

Average impact point shift per detent
Shooting distance	SG 550	SG 551
100 m	1.5 cm	1.8 cm
200 m	3.0 cm	3.6 cm
300 m	4.5 cm	5.4 cm
400 m	6.0 cm	7.2 cm

To correct the height or side, turn the corresponding correction screw with a screwdriver.

Types of ammunition for the Stgw 90

GP90 (ordonance ammunition): Standard ammunition for military exercises
Sports ammunition: For more precise hit images in competition

Markings on the cartridge case base

Markings on the cartridge case base

The base of a cartridge case contains important manufacturing markings for identifying the ammunition.

Above: A letter or symbol for the munitions factory
Below: A number indicating the year of manufacture of the cartridge

These markings help shooters and collectors to better trace the origin and quality of the ammunition.

5. maintenance and care of the Stgw 90

So that the Stgw 90 works reliablyit must be cleaned and lubricated after each use.

Assault rifle 90 (SIG SG 550) disassembled into individual parts with barrel, bolt housing, magazine, trigger mechanism, butt, rear sight and other components.

An assault rifle 90 (SIG SG 550) neatly disassembled into individual parts - ensures order and system when servicing, cleaning and maintaining the weapon.

Step-by-step instructions:

Ensure that the gun is unloaded!
Break down into main components
Cleaning the barrel with a cleaning cord or brush
Clean & lubricate lock and mechanism
Reassemble the gun and carry out a function check

⚠️ Important: Never use too much oil - this can lead to malfunctions!

Correct disassembly of the 90 assault rifle

🛠 Correctly disassembling and reassembling the 90 assault rifle - instructions for shooters

Interesting facts about the 90 / SIG 550 assault rifle

The SIG 550also known as Assault rifle 90 (Stgw 90) or Barrel 90that is Standard rifle of the Swiss Army and is one of the most accurate assault rifles in the world.
Developed in the 1980s from the Swiss Industrial Society (SIG)it became Introduced in 1986.

👉 Here are some interesting details about the SIG 550:

Is the Sturmgewehr 90 really comparable to the AK-47? 🤔

Yes, there are indeed exciting similarities between the two rifles!

Both, the SIG 550 and the AK-47, use a Proven gas pressure system with rotary head lockwhich is known for its reliability and Easy handling is known.
This system makes both weapons Extremely robust and Reliable even under the most difficult conditions like Dirt, cold or moisture.

But this is where the similarities almost end:

While the AK-47 as an icon for simplicity and mass production the SIG 550 for Swiss precision and the highest quality workmanship.
With tight tolerances and high-quality materials it was for Maximum accuracy constructed - a real differencewho has the SIG 550 one of the most accurate assault rifles in the world makes.

In short: Both are Master of their classbut with very different strengths!

How precise is the SIG 550 really? 🤔

The SIG 550 is one of the most accurate assault rifles in the world. Even on Distances of 300-400 metres hits the mark Reliably to the finish line.

With a high-quality optics are under ideal conditions even Hits at 600-800 metres possible - what a rifle in the Calibre 5.56×45 mm NATO extraordinary is.

Is the SIG 550 really as reliable as its reputation promises? 🤔

Yes, the SIG 550 is indeed considered to be extremely reliable.

Thanks to high-quality materials, precise manufacturing and one robust gas pressure system it works even under extreme conditions like Cold, snow and dirt flawless.

Developed for the demanding conditions of the Swiss Alpsit has its Reliability in numerous tests and applications proven.

What variants of the SIG 550 are available? 🤔

– SIG 551: A shorter carbine version with a more compact barrel.

– SIG 552/553: Even more compact versions for use in confined spaces (Close Quarters Battle).

– SIG 550 Sniper: A modified version with a heavy barrel and telescopic sight for sniper use.

Why does the Swiss Army use the SIG 550? 🤔

The Assault rifle 90 (SG 550) was launched in 1990 as the successor to the outdated SG 57 introduced in the Swiss Armed Forces. Several alternatives were examined before the decision was made:

– SIG SG 541Further development of the SG 540, reliable but not modular enough.

– FN FNCLightweight and inexpensive, but insufficient precision and adaptability.

– HK33: Precise and reliable, but too heavy.

– GalilRobust, but too heavy and ergonomically unsuitable.

Thanks to its high precision, modularity and reliability as well as its domestic production, the SG 550 best met the requirements of the Swiss Army and established itself as the standard rifle.

When will the assault rifle be replaced? 🤔

Currently No replacement for the assault rifle 90 planned. According to the last official response from the Head of the DDPS Department the weapon remains in use, as it is protected by Regular modernisation is kept technically up to date.

The Stgw 90 is Compatible with modern add-on systems like Telescopic sights, Night vision devices and other modules. According to the VBS, the existing quantity of weapons is sufficient probably until the year 2030.

In addition, the assault rifle only a part of the personal and group tactical armamentSoldiers additionally use Corps weapons like Light and heavy machine guns, Sniper rifles and Other weapon systems.

What are the disadvantages of the SIG 550? 🤔

– Weight: At around 4.1 kg (without magazine), it is heavier than many modern assault rifles.

– Length: The relatively long design can be impractical in confined spaces or vehicles.

– Costs: Production and spare parts are expensive due to the high-precision manufacturing.

Why do SIG 550 magazines have a transparent design? 🤔

The magazines are made of transparent polymer so that the shooter can see the remaining ammunition at all times. This practical feature is rarely found on other assault rifles.

How far can you theoretically shoot with the SIG 550? 🤔

The maximum ballistic range of the 5.56×45 mm NATO cartridge is around 3,000 metres. This means that under optimal conditions, the projectile can reach this distance before falling to the ground.

How far can you still hit accurately with the SIG 550? 🤔

– With standard sights (rear sight): Reliable hits are possible up to about 400-500 metres.

– With telescopic sight: Experienced shooters can hit targets accurately at 600-800 metres.

– Combat range: In practice, the rifle is usually used at 100-300 metres, as this is where the best penetration and accuracy is achieved.

At distances over 800 metres, the energy of the 5.56 mm cartridge decreases significantly, and even with a telescopic sight it becomes difficult to land targeted hits. Rifles with more powerful calibres such as 7.62×51 mm NATO or .338 Lapua Magnum are better suited for longer distances.

Why a sound knowledge of the 90 assault rifle is essential

The Assault rifle 90 is not only a Precise and reliable service weaponbut also a central component of Swiss shooting. However, precision and safety depend not only on the weapon, but above all on the Expertise of the shooter from.

A thorough knowledge of the technical properties, correct handling and maintenance ensures that the rifle is always Functional and ready for use remains. This is particularly important for Federal exercises, young shooters' courses and competitionswhere error-free operation is decisive for success and safety.

Anyone who not only wants to use the assault rifle 90, but really master If you want to be a professional, you have to have a sound education - be it in a club, in the army or through regular training.

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