SIG SG 540

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SG 540
Type Assault rifle
Place of origin Flag of Switzerland Switzerland
Service history
Used by See Users
Production history
Designer SIG
Designed 1970s
Manufacturer MANURHIN, INDEP, FAMAE
Produced 1977-2002[1]
Variants SG 542, SG 543
Specifications
Weight 3.52 kg (7.76 lb) fixed stock (SG 540)
3.55 kg (7.8 lb) (SG 542)
3 kg (6.6 lb) folding stock (SG 543)
Length 950 mm (37.4 in) stock extended / 733 mm (28.9 in) stock folded (SG 540)
1,000 mm (39.4 in) stock extended / 754 mm (29.7 in) stock folded (SG 542)
805 mm (31.7 in) stock extended / 569 mm (22.4 in) stock folded (SG 543)
Barrel length 460 mm (18.1 in) (SG 540)
465 mm (18.3 in) (SG 542)
300 mm (11.8 in) (SG 543)
Cartridge 5.56x45mm NATO (SG 540, SG 543)
7.62x51mm NATO (SG 542)
Action Gas operated, rotating bolt
Rate of fire 650-800 rounds/min[1]
Muzzle velocity 980 m/s (3,215 ft/s) (SG 540)
820 m/s (2,690.3 ft/s) (SG 542)
875 m/s (2,870.7 ft/s) (SG 543)
Effective range 100 to 500 m sight adjustments
Feed system 20, 30-round detachable box magazine
Sights Rear: rotating diopter (aperture); front: hooded post

The SG 540 is an assault rifle chambered in the 5.56x45mm NATO cartridge developed in the early 1970s by Schweizerische Industrie Gesellschaft (SIG, currently Swiss Arms AG) based at Neuhausen in Switzerland as a private venture primarily destined for export.

Contents

[edit] Development

Work on a new generation lightweight rifle using the 5.56 mm round began in the mid 1960s at SIG and resulted in the somewhat unsuccessful SG 530-1 design that employed a gas-assisted roller-locking delayed blowback system, which proved complicated and expensive. As a result, in 1969 SIG chose to dispense with the complex roller locking action opting instead for a new design using the more robust and simple rotating bolt locking mechanism (derived from the 7.62 mm Soviet AK-47 assault rifle). This combination was to be successful and the rifle entered production as a family of weapons consisting of: the base, 5.56 mm SG 540, the 7.62 mm SG 542 and the 5.56 mm SG 543 carbine, where both 5.56 mm weapons were designed for use with 5.56x45mm NATO M193 ammunition, while the SG 542 - the rifle caliber 7.62x51mm NATO cartridge. Production began between 1973-1974, but due to Swiss restrictions on firearms exportation it had to be carried out at the MANURHIN (Manufacture de Machines du Haut Rhin) facility in Mulhouse, France. The SG 540 series has entered service with the armed forces of several countries in Africa, Asia and South America as well as numerous law enforcement and security agencies. In 1988, the nationally-owned, Portuguese defense firm INDEP purchased rights to license build the SG 543 carbine. Currently both the SG 540 and SG 542 are only manufactured under license in Chile, by FAMAE. Based on the SG 540, FAMAE developed a 9 mm submachine gun version of the rifle known as the FAMAE SAF.

[edit] Design details

The SG 540 is a gas-piston driven automatic rifle that fires from a closed bolt position. SIG designers used an extended travel piston system (with the recoil spring wrapped around the piston rod itself) and an adjustable gas regulator with three settings: "0" - used to launch rifle grenades, "1" - used for normal operation and "2" - used only in conditions of heavy fouling. The firearm's rotating bolt is locked into position by two steel locking lugs. The bolt head is rotated by a control cam and guiding surface located in the bolt carrier used to disengage the locking lugs during rearward motion. The extractor is contained in the bolt assembly while a protrusion in the upper receiver housing acts as the fixed ejector.

The rifle has a hammer-type striker and a fire control selector that is also the safety (lever in the "S" position - indicates the gun is safe, "1" - semi-automatic fire, "3" - 3 round burst and "20" - full auto fire). The SG 540 is fed from either 20 or 30-round, double column box magazines. After the last round is fired, a hold open device in the magazine engages the bolt catch that locks the bolt in its rear (open) position. A bolt release button is located at the left side of the receiver.

The rifled barrel is fitted with a flash suppressor, which is also used to attach rifle grenades and a bayonet. The iron sights consist of a hooded foresight that can be corrected in elevation and an adjustable (windage only), rotating rear drum that contains four apertures used for firing at: 100, 300, 400 and 500 m. The receiver housing top cover can be used to mount adapters enabling the use of optics.

The SG 540 series come equipped with either a fixed or a side-folding, metal skeleton stock. Another standard feature is a folding bipod which is stowed under the handguard when not in use. The fixed stock, pistol grip and handguard are all made of high-strength polymers to reduce overall weight. In order to minimize costs, metal stamping was employed in the production process.

[edit] Variants

Differences between the SG 542 and the SG 540 are mainly the result of adopting a more powerful, full-size rifle cartridge. The SG 542 also uses 20/30-round box magazines but the sights were modified with a 600 m setting in addition to the 100, 300 and 500 m sight drum positions.

The SG 543 carbine is a shortened variant of the SG 540 that has been modified with a shorter barrel, gas tube and piston as well as a shorter handguard and sights fixed at: 100, 200, 300 and 400 m. The SG 543 lacks the integral bipod of the SG 540/542 and the reduced barrel cannot be used to fire rifle grenades. The SG 540 served as the basis for the SG 541 prototype, which would later become the SG 550 that entered service with the Swiss Armed Forced as the Stgw 90.

Additionally, two semi-automatic variants were manufactured by MANURHIN between the late 1970s and the early 1980s specifically for the European civilian market: called the SIG Manurhin F.S.A. and the SIG Manurhin C.S.A.. These rifles were chambered in .222 Remington and .243 Winchester respectively. Both were available with a 30-round or reduced 5-round magazines, and the option of a folding or fixed stock. The unusual chambering for this type of military-style rifle was an attempt to comply with regulations in certain European countries posing restrictions on the civilian ownership of "military" cartridges such as the 5.56x45mm NATO/.223 Remington or 7.62x51mm NATO/.308 Winchester.

[edit] Users

[edit] See also

[edit] References

  • Long, Duncan. (1989). Assault Pistols, Rifles And Submachine Guns, Boulder: Paladin Press
  • sigarms.com
  1. ^ a b Hogg, Ian; Gander, Terry (2005). Jane's Guns Recognition Guide, 4th edition, New York, NY: HarperCollins Publishers, 323. ISBN 0-00-718328-3. 

[edit] External links