The Sturmgewehr 57 with folded down iron sights
Type Automatic rifle
Place of origin Switzerland
In service 1957–present
Used by Switzerland, Bolivia, Chile
Designer Rudolf Amsler
Manufacturer Schweizerische Industrie Gesellschaft (SIG), Beretta
Variants SG 510-1, SG 510-2, SG 510-3, SG 510-4
Weight 5.7 kg (12.57 lb) (Stgw 57)
4.37 kg (9.63 lb) (SG 510-4)
Length 1,100 mm (43.3 in) (Stgw 57)
1,015 mm (40.0 in) (SG 510-4)
Barrel length 583 mm (23.0 in) (Stgw 57)
505 mm (19.9 in) (SG 510-4)
Cartridge 7.5×55mm GP 11 (Stgw 57)
7.62×51mm NATO (SIG 510-4)
Action Roller-delayed blowback
Rate of fire 450–600 rounds/min
Muzzle velocity 750 m/s (2,460 ft/s)
Effective range 640 m (700 yd) iron sights
600 m (656 yd) Kern 4×24 optical sight
Feed system 20, 24, 30-round detachable box magazine
Sights Front post, rear aperture
The SIG SG 510 or Sturmgewehr 57 is an automatic rifle manufactured by Schweizerische Industrie Gesellschaft (now SAN Swiss Arms) of Switzerland. It uses a similar roller-delayed blowback system to the H&K G3 and CETME rifles.
The SIG SG 510-1 entered service in the Swiss Army with the designation Fass 57 (French, for Fusil d' Assaut 57) or Stgw 57 (German for Sturm Gewehr 57).
The Sturmgewehr 57/SIG SG 510-1 was adopted for Swiss military service in 1957. The Stgw 57 has been gradually replaced by the lighter SIG SG 550 but is still in active service with reservists who have not had a chance to be upgraded to the SG 550.
The SG 510 is derived from the AM55 used during the 1950s. It is a selective-fire assault rifle that employs a roller-delayed blowback operating system.
The weapon is mainly made of pressed sheet-metal components to ease mass production. The SG 510 has a distinctive T-shaped bolt handle similar to the earlier K-31. The butt-stock and hand guard of the rifle are rubberized for comfort and durability—a feature totally unique among rifles—and the front hand guard is ribbed to provide a better grip.
The SG 510-1/Stgw 57 barrel is rifled along 520 mm (20.5 in) of its length and has a 270 mm (1 in 10.6 in) 4 groove rifling. At the end of the barrel an integral muzzle brake is fitted that reduces recoil by about 25%. The barrel is surrounded by a perforated tubular barrel jacket with two mounting points for an integral bipod—one near the muzzle, and another near the receiver.
SG 510-4 rifle chambered in 7.62×51mm NATO
The SG 510-4 chambered in 7.62×51mm NATO with a 305 mm (1 in 12 in) twist rate barrel was adopted by Chile and Bolivia. The SIG SG 510 is officially classed as an automatic rifle but served as a designated marksman weapon (in Chile with Supra 4×24 scope).
For recoil reduction the fixed butt-stock is fitted with a recoil buffer. The SG 510-1/Stgw 57 spots a large carrying handle at its balance point that can be used during quick position changes or on the march. On the right hand side of the rifle, there is a foldaway trigger which enables the operator to use the rifle with arctic mittens. It also improves accuracy, because it reduces the force needed to pull the trigger.
The trigger mechanism has a three-position fire selector switch that is also the manual safety toggle that secures the weapon from accidentally discharging. The user selects the operating mode with a large side lever on the left side of the receiver that can be rotated to select S (safe), E (semi-automatic fire) or M (full-automatic fire).
Swiss Army Stgw 57 with erected iron sights and PE57 bayonet
The SG 510-1/Stgw 57 has a straight-line stock design, and an elevated iron sights line. Both the front and rear sights can be folded down when not in use. The rear peep sight of the Stgw 57 can be adjusted from 100 m to 640 m. From 100–200 m the sight adjusts in 50 m increments. From 200–300 m in 30 m increments, and from 300–640 m in 20 m increments.
According to the Swiss Army the 50 % windage and elevation dispersion shot at 300 m from a machine rest averages 6 cm (2.4 in). For anti-personnel use, the SG 510-1/Stgw 57 typical maximum range for consistent accuracy is 600 m (656 yd).
For designated marksman use, the SG 550 can be equipped with a quick-detachable Kern 4×24 telescopic sight. The sight weighs 730 g (26 oz) and includes a variety of features, such as mounting components, a Bullet Drop Compensation (BDC) elevation adjustment knob for ranges from 100 to 600 m, an illuminated reticle that enables target acquisition in low-light conditions and a diopter eyesight correction adjustment. Included with the sight is a lens hood for mounting on the ocular that reduces image quality-impairing stray light and a gray filter for glare reduction. A night vision sight with an infra red light can also be mounted. The Chilean version can fit a German-made Supra 4×24 telescopic sight.
The Swiss Army Stgw 57 is fed from curved detachable box magazines, made from steel and containing 24 rounds. Magazines with 20 and 30-round capacities are however available. Other accessories include the sling, the PE57 bayonet, and a special small-capacity magazine for grenade-launching cartridges.
Rifle grenades can be launched without adding a special provision. Grenade-launching cartridges enable the SG 510-1/Stgw 57 to fire Gewehrgranaten 58 rifle grenades. The rifle grenade 58 achieves a muzzle velocity of 35 m/s and a maximum range of 125 m without the help of a booster charge or 70 m/s and a maximum range of 400 m with the help of a booster charge. The rifle grenade 58 may be fitted with the following warheads:
* Hollow charge for heavy armour. Modem hollow charge rifle grenades can penetrate 300 to 500 mm (12 to 20 in) of "best quality" armour plating.
* Anti-personnel with impact detonator.
* Smoke canister for reducing visibility.
 Civilian use
Upon completion of their military service, members of the Swiss armed forces can obtain ownership of their personal SG 510 rifle by paying an administrative fee. These "civilianised" rifles are converted to a semiautomatic only configuration. As of 2007, around 40 percent of discharged soldiers choose to retain their weapon, and the going rate for civilianised SG 510 rifles on the private weapons market is reported to vary between 400 and 500 Swiss francs.
In Switzerland the SG 510 is also used for target shooting matches. For this the standard iron sights can be replaced by target shooting diopter and globe sight sighting lines. When the sighting line radius is kept at its original length Swiss sport shooters refer to a such modified rifle as Stgw 57/02. When the sighting line radius is lengthened by mounting the globe sight nearer to the muzzle it is referred to as Stgw 57/03.
* 510-1: Standard Swiss service rifle.
* 510-2: Lightened variant of the standard rifle.
* 510-3: 7.62×39mm variant with shorter barrel. This was produced in small numbers as a prototype and offered to the Finnish Army. They did not want it, hence, this model of the rifle was never mass-produced.
* 510-4: 7.62×51mm NATO variant used by Bolivia and Chile.
* AMT: semi-automatic only variant imported into the United States in relatively small numbers. It was available in both .308 (7.62×51) and 7.5×55mm GP 11 Swiss, with the latter being less common. "AMT" stood for "American Match Target". It was equipped with fine wooden furniture and a rounded upper handguard.
* SIG PE 57: semi-automatic only civilian version available in 7.5×55mm GP 11 Swiss. This variant is not the same as privatised former Swiss Army service rifles.