SIG-510
Summary
| Country | 🇨🇭 Switzerland |
| Category | Assault rifle |
| Manufacturer | Sig Sauer |
Technical specifications
| SIG-510 | |
|---|---|
| Fire Rate | 600 rounds/min. |
| Caliber | 7,5 mm GP11 |
| Magazine | 6 - 24 rounds |
| Length | 1105 mm (43.5 in) |
| Weight | 5.7 kg (12.6 lb) |
| Range | 600 m (1969 ft) |
Description
The SG 550 assault rifle is manufactured by SIG Sauer AG. The designation "SG" is an abbreviation for Sturmgewehr (assault rifle). The rifle's design is based on the earlier SIG SG 540 series. Development commenced in 1978 when the Swiss armed forces sought a successor to the Stgw 57 battle rifle, requiring:
- Modularity
- Various configurations including a carbine
- Reduced weight
- Accuracy out to 300 meters.
Two designs were considered: the W+F C42 and the SIG SG 541. The SIG 5.6×45mm Gw Pat 90 cartridge, the Swiss equivalent to 5.56×45mm NATO, was chosen. The decision to adopt the SG 541 was announced in 1983 and it was later designated SG 550 and SG 551. Production began in 1986, leading to official acceptance into service as the Stgw 90 in 1990. Over 600,000 rifles have been delivered, with military production now ceased.
The SG 550 is a selective-fire 5.56×45mm NATO assault rifle firing from a closed bolt. It employs a gas-actuated, piston-driven, long-stroke operating system derived from the SG 540 series, featuring an adjustable gas valve. Locking is performed by a rotary bolt with two lugs, like the mechanism used in the SG 540. The rifle is hammer-fired and includes an ambidextrous safety and a four-setting fire selector (safe, single fire, 3-round burst, full automatic). It is fed by translucent polymer box magazines available in multiple capacities that can be locked together. A bolt hold-open device is present. The design incorporates a side-folding skeletonized polymer buttstock and a folding aluminum bipod. The steel receiver and components are finished with a ceramic-reinforced enamel coat. The cold hammer-forged barrel is equipped with a flash suppressor functioning as a rifle grenade launcher adapter and bayonet lug. Standard barrel twist is 254 mm (1:10 in) for Swiss GP 90 ammunition, with a 178 mm (1:7 in) twist available for export. Accuracy is assessed by R50 dispersion at 300m. Iron sights include a rear rotating diopter and hooded front post, adjustable for windage and elevation, with tritium inserts for night use. Quick-detachable mounts and integral rails allow for the attachment of telescopic sights and other optics. Standard accessories include a spare magazine, sling, cleaning kit, and loading aid, with optional underbarrel grenade launchers and bayonets also supported.
Key variants include the SG 551 carbine, characterized by a shorter barrel and modified features compared to the SG 550, lacking its bipod, rifle grenade, and bayonet capability. SG 551 variants include police, SWAT, and a longer-barreled (LB) version. The compact SG 552 Commando featured an even shorter barrel and a different bolt carrier/recoil system before being replaced by the SG 553 in 2008. The SG 553 incorporates a revised recoil spring arrangement addressing issues of the SG 552. SG 553 variants include the LB, the SG 553 R chambered in 7.62×39mm, and the SG 553 BK in .300 AAC Blackout. A conversion kit allows modifying an SG 552 to the SG 552-A1 standard. The SG 550-1 Sniper is an accurized model with a heavy barrel developed for police use. Semi-automatic configurations for civilian markets exist under various designations such as SP, PE 90, and SIG Sport. U.S. civilian models like the SIG 556 series were domestically assembled and often featured adaptations such as M16 magazine compatibility; these specific SIG 556 series were later discontinued. Regulatory classifications, such as those in Canada affecting the PE 90, have influenced the availability of civilian variants. The SIG 522LR is a separate .22-caliber sporting model styled after the SG 551.
The SG 550 rifle series is utilized by the Swiss armed forces as the Stgw 90 and by the Swiss Police with the SG 550-1 Sniper variant. Certain variants of the SG 551 are designed for use with security and special forces.