SIG SG 540
Encyclopedia
The SG 540 is a 5.56mm
5.56x45mm NATO
5.56×45mm NATO is a rifle cartridge developed in the United States and originally chambered in the M16 rifle. Under STANAG 4172, it is a standard cartridge for NATO forces as well as many non-NATO countries. It is derived from, but not identical to, the .223 Remington cartridge...

 assault rifle
Assault rifle
An assault rifle is a selective fire rifle that uses an intermediate cartridge and a detachable magazine. Assault rifles are the standard infantry weapons in most modern armies...

 developed in the early 1970s by Schweizerische Industrie Gesellschaft
Schweizerische Industrie Gesellschaft
Schweizerische Industrie Gesellschaft , or SIG, is the former name of SIG Holding AG, a Swiss company that has been active in various businesses during its more than 150 years of operation. Since the year 2000 the Society has undergone strategic refocus, concentrating on its core compentence in...

 (SIG, currently SAN Swiss Arms AG) based out of Neuhausen
Neuhausen am Rheinfall
Neuhausen am Rheinfall is a municipality in the canton of Schaffhausen in Switzerland.The little town is well known for the Rhine Falls, a tourist attraction and mainland Europe's largest waterfall....

, Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....

 as a private venture primarily destined for export markets and as a potential replacement for the 7.5mm SG 510 automatic rifle
Automatic rifle
Automatic rifle is a term generally used to describe a semi-automatic rifle chambered for a rifle cartridge, capable of delivering both semi- and full automatic fire...

 known as the Stgw 57 in Swiss service.

History

Work on a new generation of lightweight rifle using the intermediate 5.56mm round began at SIG in the 1960s and resulted in the somewhat unsuccessful SG 530-1
SIG SG 530
The SIG 530 was a Swiss assault rifle developed in the 1960s by Schweizerische Industrie Gesellschaft to take the then-new 5.56x45mm NATO round.-Development:...

 design that employed a gas-assisted
Gas-operated reloading
Gas-operation is a system of operation used to provide energy to operate autoloading firearms. In gas-operation, a portion of high pressure gas from the cartridge being fired is used to power a mechanism to extract the spent case and chamber a new cartridge. Energy from the gas is harnessed...

 roller-delayed blowback operating mechanism which proved too complicated and expensive to manufacture. As a result, in 1969 SIG chose to dispense with the complex roller-delayed action opting instead for a design using the more robust and simple piston-operated rotating bolt
Rotating bolt
Rotating bolt is a method of locking originally developed by Ferdinand Ritter von Mannlicher and found in his Steyr-Mannlicher M1895 straight-pull bolt-action rifle designed for and issued to the Austro-Hungarian Army...

 locking mechanism (derived from the Soviet
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

 7.62mm AK
AK-47
The AK-47 is a selective-fire, gas-operated 7.62×39mm assault rifle, first developed in the Soviet Union by Mikhail Kalashnikov. It is officially known as Avtomat Kalashnikova . It is also known as a Kalashnikov, an "AK", or in Russian slang, Kalash.Design work on the AK-47 began in the last year...

 assault rifle). This combination was to be successful and the rifle entered production as a family of weapons consisting of the base 5.56mm SG 540, the 7.62mm SG 542 battle rifle and the 5.56mm SG 543 carbine
Carbine
A carbine , from French carabine, is a longarm similar to but shorter than a rifle or musket. Many carbines are shortened versions of full rifles, firing the same ammunition at a lower velocity due to a shorter barrel length....

, where both 5.56mm variants were designed for use with 5.56x45mm NATO M193 ammunition, while the SG 542—the full size 7.62x51mm NATO rifle cartridge.

Production began between 1973–1974, but due to Swiss federal restrictions on firearms exportation, manufacturing had to be carried out at the MANURHIN (Manufacture de Machines du Haut Rhin) facility in Mulhouse
Mulhouse
Mulhouse |mill]] hamlet) is a city and commune in eastern France, close to the Swiss and German borders. With a population of 110,514 and 278,206 inhabitants in the metropolitan area in 2006, it is the largest city in the Haut-Rhin département, and the second largest in the Alsace region after...

, France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

.

The SG 540 series has entered service with the armed forces of several countries in Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

, Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

 and South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

 as well as numerous law enforcement and security services. In 1988, the nationally-owned Portuguese
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...

 defense manufacturer INDEP
INDEP
INDEP - Indústrias Nacionais de Defesa, EP , originally Fábrica do Braço de Prata , is a defense industry company owned by the Portuguese Government...

 purchased rights to license build the SG 543 carbine for its own forces. Currently both the SG 540 and SG 542 are only manufactured in Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

, under license by FAMAE
FAMAE
FAMAE is a Chilean government-owned weapons producer. Its products are used by the Chilean armed forces and the police. The company produces among others the FAMAE CT-30 carbine, FAMAE SAF submachine gun, FAMAE FD-200 sniper rifle, Cohete Rayo rocket launcher and FAMAE revolver...

 for the Chilean Armed Forces. Based on the SG 540, FAMAE developed a 9mm submachine gun
Submachine gun
A submachine gun is an automatic carbine, designed to fire pistol cartridges. It combines the automatic fire of a machine gun with the cartridge of a pistol. The submachine gun was invented during World War I , but the apex of its use was during World War II when millions of the weapon type were...

 version of the weapon known as the SAF
FAMAE SAF
The FAMAE SAF is a submachine gun produced since 1993 by FAMAE , the Chilean government small arms factory...

.

Operating mechanism

The SG 540 is an air-cooled, gas-operated
Gas-operated reloading
Gas-operation is a system of operation used to provide energy to operate autoloading firearms. In gas-operation, a portion of high pressure gas from the cartridge being fired is used to power a mechanism to extract the spent case and chamber a new cartridge. Energy from the gas is harnessed...

, selective fire
Selective fire
A selective fire firearm has at least one semi–automatic and one automatic mode, which is activated by means of a selector which varies depending on the weapon's design. Some selective fire weapons utilize burst fire mechanisms to limit the maximum or total number of shots fired automatically in...

 assault rifle that fires from a closed bolt
Closed bolt
A semi or full-automatic firearm which is said to fire from a closed bolt is one where, when ready to fire, a round is in the chamber and the bolt and working parts are forward...

 position. SIG designers used a long-stroke piston-driven action (with the recoil spring wrapped around the piston rod itself) and an adjustable gas regulator with three settings: "0"—used to launch rifle grenade
Rifle grenade
A rifle grenade is a grenade that uses a rifle-based launcher to permit a longer effective range than would be possible if the grenade was thrown by hand...

s, "1"—used in normal operating conditions and "2"—used in extreme environmental conditions or in the presence of heavy fouling. The firearm is locked into battery by means of a rotating bolt
Rotating bolt
Rotating bolt is a method of locking originally developed by Ferdinand Ritter von Mannlicher and found in his Steyr-Mannlicher M1895 straight-pull bolt-action rifle designed for and issued to the Austro-Hungarian Army...

 which features two heavy steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

 locking lugs. The bolt head is rotated by a control cam riding in a helical guide slot machined into the bolt carrier. When a shot is fired, propellant gases from the barrel are fed into the gas cylinder located above the barrel and impart rearward pressure on the piston rod, which drives the bolt carrier back. After a certain amount of free travel built into the system to allow the projectile to depart the barrel, residual gas pressures in the bore drop to a safe level, allowing the breech to be opened. The cam slot in the bolt carrier proceeds to actuate the camming stud in the bolt, rotating the bolt head out of engagement with the locking abutments in the receiver. The spent cartridge casing is extracted by a claw extractor contained in the bolt assembly while a protrusion on one of the internal bolt carrier guide rails in the upper receiver acts as the fixed ejector, removing the casing through a port on the right side of the receiver housing.

Features

The rifle is hammer-fired and has a fire control selector mechanism 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"—fully automatic fire). The SG 540 is fed from either 20 or 30-round staggered box magazines. After the last round is fired, a hold-open tab in the magazine engages the bolt catch that locks the bolt in its rear (open) position. A bolt release button is located on the left side of the receiver.

The rifled
Rifling
Rifling is the process of making helical grooves in the barrel of a gun or firearm, which imparts a spin to a projectile around its long axis...

 barrel is fitted with a flash suppressor
Flash suppressor
A flash suppressor, also known as a flash guard, flash eliminator, flash hider, or flash cone, is a device attached to the muzzle of a rifle or other gun that reduces the visible signature of the burning gases that exit the muzzle. This reduces the chances that the shooter will be blinded in dark...

, which is also used to attach rifle grenade
Rifle grenade
A rifle grenade is a grenade that uses a rifle-based launcher to permit a longer effective range than would be possible if the grenade was thrown by hand...

s and a bayonet
Bayonet
A bayonet is a knife, dagger, sword, or spike-shaped weapon designed to fit in, on, over or underneath the muzzle of a rifle, musket or similar weapon, effectively turning the gun into a spear...

. The iron sight
Iron sight
Iron sights are a system of shaped alignment markers used as a sighting device to assist in the aiming of a device such as a firearm, crossbow, or telescope, and exclude the use of optics as in telescopic sights or reflector sights...

s consist of a hooded foresight that can be corrected in elevation and an adjustable (windage only), rotating rear drum that contains four apertures with settings for firing at: 100, 300, 400 and 500 m. The receiver top surface can be used to mount adapters enabling the use of optics.

The SG 540 series come equipped with either a fixed buttstock or a side-folding metal skeleton stock. Another standard feature is a folding bipod
Bipod
A bipod is a support device that is similar to a tripod or monopod, but with two legs. It provides significant stability along two axes of motion .-Firearms:...

 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.

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 normally 20/30-round box magazines (5 and 10 magazines were also manufactured) 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 short 300 mm (11.8 in) barrel, a shorter gas cylinder and piston rod as well as a different handguard and sights with 100, 200, 300 and 400 m firing range positions. 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
SIG SG 550
The SG 550 is an assault rifle manufactured by Swiss Arms AG of Neuhausen, Switzerland...

 that entered service with the Swiss Armed Forces as the Stgw 90 (Sturmgewehr 90).

Additionally, two semi-automatic variants were manufactured by MANURHIN between the late 1970s and the early 1980s specifically for the Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

an civilian market: called the SIG Manurhin F.S.A. and the SIG Manurhin C.S.A.. These rifles were chambered in .222 Remington
.222 Remington
The .222 Remington aka the Triple Deuce/Triple Two/Treble Two is a centerfire rifle cartridge introduced in 1950, and was the first commercial rimless .22 cartridge made in the United States...

 and .243 Winchester
.243 Winchester
The .243 Winchester is a popular sporting rifle cartridge. Initially designed as a varmint round, it is now more frequently used on medium to large game such as whitetail deer, mule deer, pronghorn, wild hogs, and even black bear and caribou...

 respectively. Both were available with either 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 imposing restrictions on the civilian ownership of "military" cartridges such as the 5.56x45mm NATO
5.56x45mm NATO
5.56×45mm NATO is a rifle cartridge developed in the United States and originally chambered in the M16 rifle. Under STANAG 4172, it is a standard cartridge for NATO forces as well as many non-NATO countries. It is derived from, but not identical to, the .223 Remington cartridge...

/.223 Remington
.223 Remington
The .223 Remington is a sporting cartridge with almost the same external dimensions as the 5.56×45mm NATO military cartridge. The name is commonly pronounced either two-two-three or two-twenty-three. It is loaded with a diameter, jacketed bullet, with weights ranging from , though the most common...

 or 7.62x51mm NATO/.308 Winchester
.308 Winchester
The .308 Winchester is a rifle cartridge and is the commercial cartridge upon which the military 7.62x51mm NATO centerfire cartridge is based. The .308 Winchester was introduced in 1952, two years prior to the NATO adoption of the 7.62x51mm NATO T65...

.

Users

Uses the SG 542 variant.: Uses the SIG-FAMAE SG 542-1, SG 540 and SG 543 variants. Produced under license by FAMAE.: Produced under license by Manurhin and temporarily used by the French army
French Army
The French Army, officially the Armée de Terre , is the land-based and largest component of the French Armed Forces.As of 2010, the army employs 123,100 regulars, 18,350 part-time reservists and 7,700 Legionnaires. All soldiers are professionals, following the suspension of conscription, voted in...

. Replaced by the FAMAS
FAMAS
The FAMAS is a bullpup-styled assault rifle designed and manufactured in France by MAS located in Saint-Étienne, which is now a member of the French government-owned Nexter group...

 in the early 1980s.: Portuguese army
Portuguese Army
The Portuguese Army is the ground branch of the Portuguese Armed Forces which, in co-operation with other branches of the Portuguese military, is charged with the defence of Portugal...

.

See also

  • SG 510
    SIG 510
    The SIG SG 510 or Sturmgewehr 57 is an automatic rifle manufactured by Schweizerische Industrie Gesellschaft of Switzerland. It uses a similar roller-delayed blowback system to the H&K G3 and CETME rifles...

    , the previous service rifle but still in service.
  • SG 550, Switzerland's current service rifle.
  • Assault rifle
    Assault rifle
    An assault rifle is a selective fire rifle that uses an intermediate cartridge and a detachable magazine. Assault rifles are the standard infantry weapons in most modern armies...

  • Gun politics in Switzerland
    Gun politics in Switzerland
    Gun politics in Switzerland are unique in Europe. The personal weapon of militia is kept at home as part of the military obligations. Switzerland has one of the highest militia gun ownership rates in the world. In recent times political opposition has expressed a desire for tighter gun regulations...


External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK