A superior concept, programmed for success
The new SIG assault rifle series SG 550/551 are built and tested in accordance with state-of-the-art manufacturing and quality assurance criteria. The design concept
employs the proven combination of gas operation and rotating bolt, providing the
weapons with utmost dependability, even under the most extreme field conditions.
These new SIG assault rifles are available in two versions: the standard model SG 550
and the SG 551 short pattern. As such, they effectively form a weapon family,
sharing a majority of common components. Consequently, handling, training and
maintenance are identical for both models.
The standard version is equipped with a bipod. Given the optimal weapon layout,
accurate shooting in all positions is enhanced. The heavy barrel, hammer-forged in
one operation to form chamber and bore, the long sight base and the carefully matched
sighting elements provide superior inherent accuracy.
The functionally mature and weight-saving design concept provides advantages such
as increased combat readiness plus additional features such as 3-round burst, folding
butt and bolt hold-open catch.
Highly accurate, lightweight and rugged
SIG's state-of-the-art production processes and manufacturing know-how guarantee
their weapons' superior quality and combat readiness. In practical terms this
represents: extreme precision, low weight factor and ruggedness. As with all previous
SIG assault rifles, the SG 550/551 are simple and safe handling weapons that have been
proven in troop trials to be functionally dependable.
The SIG assault rifles SG 550/551 can be operated with one hand by both left- and
right-handed shooters. The ambidextrous selective-fire catch can be operated with
the shooting hand, thus eliminating any need to change position. Spent casings are
ejected approximately five meters forward of the shooter, thereby eliminating the
need for any type of case deflector.
Another convincing feature is the system of lightweight, transparent magazines which
can be clipped together and changed rapidly. Rifle grenades are launched with
standard, live ammunition. The weapon cycles automatically and therefore remains
operational at all times.
All weapons are designed to accept night vision equipment and telescopic sights
(STANAG system). To this end, a quick-detach scope mount is available which
directly accepts STANAG-based optics. Its precision fit ensures zero-retention
even after repeated mountings.
Mounted on the receiver housing is a combined diopter and snapshooting rearsight
assembly which is calibrated for selected ranges. It is adjustable to provide windage
and elevation correction. For night firing, illuminated markings are standard.
Consequently, when adjustments are made to the day sights, correction of the night
markings is automatic. The foresight assembly, comprising the protective tunnel and
the flip-up night sight with integrated light source, is fixed. As the overall sighting
line is low, the exposure silhouette presented by the shooter is minimized.
|The new models SG 550/551 SP meet NATO test
specifications and all other demanding requirements imposed for
an optimal infantry weapon, namely:
- Heavy, fixed barrel with chamber and bore hammer-forged simultaneously
- Excellent trigger that breaks crisp and clean after taking the slack out
- Optimal diopter and snapshooting sights, adjustable for windage and elevation
- On-the-weapon folding bipod fitted into a recessed handguard (SG 550 SP)
- Rugged, yet simple, design concept employing a proven gas system and rotating bolt
- Virtually closed weapon system
- Night sights, with integrated light source, on front and rear sights
- Mounts designed to accept light intensifier or infra-red sights
Superior handling characteristics
- Ergonomically correct stock design for fast locking into the shoulder and quick target
- Ambidextrous design for left- and right-handed individuals
- All controls within easy reach
- Magazine "multipack" system and bolt hold open device for rapid magazine change
- Fast and easy handling required during combat situations... also providing for quicker
proficiency in training
Low weight factor
- High-grade synthetics are used for the butt, handguard, pistol grip and magazine
- Application of sophisticated weight-saving design concepts enhances mobility and reduces shooter fatigue
- Low sighting line mated to the correct stock angle
- Well designed pistol grip which places shooting hand in close alignment with bore axis
A clear-cut decision for the Swiss Army
In exhaustive comparitive trials, the outstanding performance and inherent attributes of the SIG 550/551 assault rifles clearly established their overall superiority. In consequence, the new infantry weapons of the Swiss Army bear the name of SIG. General issue to the troops begins in the 90's - hence the Swiss designation of Assault Rifle 90 (Stgw 90).
Field-qualified for training and combat
Dust, sand mudbath tests. Low temperature and winter trials under extreme
conditions in the Swiss alps. Troop trials with live ammunition. Barrel erosion
firings during development of the ammunition. All these trials and tests served to
establish the overriding quality of the SIG assault rifles SG 550/551. They also earned
this new weapon family the simple, meaningful qualification issued by Swiss Army of
The SIG assault rifles of the SG 550/551 series are a weapon family. A maximum of
common components and identical operation between weapons greatly simplifies
training and logistics. New design methods and applied weight-saving concepts for
both models eliminate the need for tools when field stripping or in the event of major
takedowns. Consequently, the weapons can be rapidly stripped, cleaned and assembled
for immediate readiness. Component interchangeability reduces downtime to an
The SG 550/551 series are extremely rugged weapons. They are designed to limit
the ingress of mud, dust, dirt or sand. In extreme cases, the trooper can close the
bolt manually. The gas valve has two settings to ensure reliable cycling, even under
the most extreme conditions.
Marksmanship qualification at 300m range, as is standard practice in Switzerland, or
the training of sharpshooting special units calls for weapons with particularly high
inherent accuracy. The SIG assault rifles SG 550/551 meet this, and related,
requirements. Accurate marksmanship with these weapons is enhanced by
a variety of factors, including: an overall sophisticated weapon concept, equal
suitibility for left- and right-handers and exceptional inherent precision.
The particular weapon layout of the SIG assault rifles SG 550/551 provides a low
sighting line, resulting in a minimal exposure silhouette of the firer. The shooting
hand (left or right) is located close to the bore axis. Also, the handguard has been
extended well forward to allow unrestricted firing in any position. Single-shot,
fully-automatic and 3-round burst modes permit the firepower to match the combat
situation. The exceptionally low weight factor for an accurate assault rifle enhances
mobility. This, in turn, increases firepower in assault situations, or the staying power
of the individual trooper in other combat conditions. In close-quarter battle, the folding
butt turns the SIG assault rifles SG 550/551 into handy and effective sidearms.
The SG 550/551 fire 5.56mm caliber ammunition. Barrel rifling twist is matched to
suit the ammunition. Standard, live ammunition is used to launch rifle grenades. The
weapon cycles automatically and remains ready to fire at all times. Ammunition in
5.56mm (.223) caliber has excellent external and terminal ballistic properties. The
lightweight plastic magazines can be clipped together to form multipacks. This
feature, in combination with the automatic bolt hold-open catch, permits very fast
The SIG assault rifles SG 550/551 are equipped with night sights which are integrated
in the diopter drum and the flip-up foresight. Additional accessories include a carrying
sling, bayonet, cleaning kit and loading aid for rapid magazine filling. All SIG assault
rifles SG 550/551 are equipped as standard with mounts to accept telescopic sights or
night vision equipment (STANAG system).