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The Vault

SIG Stgw 57

The Stgw 57 was Switzerland’s first standard-issue selfloading service rifle. The Swiss experimented with designs for ten or twelve years (including the AK52) before adapting the model 57 in, appropriately, 1957. The design is based on the German roller-locking system, and uses a delayed blowback system like the StG45 rather than a truly locked mechanism.

The Swiss originally developed the rifle for the 7.5×55 GP11 cartridge, and designated the rifle Stgw57 for military use and SIG 510 for export sales. These rifles used a curved 24-round box magazine. Several other variants were also made for export, primarily the SIG 510-4 and AMT (American Match Target). Both of these was chambered for 7.62 NATO and used 20-round straight magazines. The American rifles were semi-auto only, and some were imported in the original 7.5 Swiss caliber (these were designated PE-57). Only about 4000 AMTs were imported into the US, and they remain a rare rifle in the country.

The Stgw57 is a very finely machined rifle, and includes several notable features. As with all roller-delayed designs, the roller recesses in the receiver will eventually wear down, and begin to increase the cartridge headspace. The German rifles (HK91 etc) accept this as the functional service life of the rifle, but the SIG has interchangeable locking recesses, so they can be replaced when worn. The sights on the export guns are a basic sliding aperture, but the Swiss issue guns use a micrometer type folding rear sight very reminiscent of the German FG42.

The Stgw57 was the primary Swiss infantry rifle until the 1980s, when the SIG 550 was adopted to replace it. The Stgw57 was also adopted by the Bolivian and Chilean armies. A version in 7.62x39mm (the 510-3) was developed for trials in Finland, but ultimately not put into production.



SIG AMT manualSIG PE57 manualStgw57 Technical manualStgw 57 Parts CatalogStgw 57 ManualPE57 sales brochureSIG 510 manual



Sig Stgw 57 and AMT photos (click here to download high resolution copies):



BiggerHammer.net has a resource section on the SIG AMT/510 with good information and a couple reprinted articles.

9 comments to SIG Stgw 57

  • David C. Carlson

    As noted, a number of these SIG rifles in 7.62x51mm were bought by Chile and Bolivia. In a recent Icíar Bollaín Spanish film that takes place in Bolivia during the recent “water war,” _Even the Rain/ Tambien la lluvia_ there are scenes of Bolivian troops clubbing demonstrators with the butt-stocks of old SIG AMT rifles.

  • Tyler Abeyta

    Very informative! I very much appreciate the german machine guns, quality, reliability and especially how SIG has kept up on little cosmetic similarities on newer rifles as the did on the old(pistol grip, slotted heat shield, and some circle sights.

  • Mike Bonomo

    I actually got to hold a PE57 in my hands back in the 80s. From what I remember it LOOKED very cool but was quite heavy. I wouldn’t want to lug one around for any distance. Kinda strange that a country that always declares neutrality and never gets involved (directly) in European problems puts so much emphasis on weapons. Not like anyone ever makes plans to invade Switzerland.

    • peter

      Kinda strange that a country that always declares neutrality and never gets involved (directly) in European problems puts so much emphasis on weapons. Not like anyone ever makes plans to invade Switzerland.

      if you have German as a neighbor you would change your opinion.

      american legion member

  • Ian

    So the rearward motion generated by firing acts upon the “bolt carrier” to the rear of the bolt, which compresses against the recoil spring to it’s rear while the forward part i.e. The bolt is locked via the rollers into the recesses in the receiver, the movement of the carrier unlocks the bolt by allowing the rollers in the bolt to compress via it’s shaped surfaces retracting.

    The Hk versions have a bar attached or formed from the bolt carrier though don’t they which also gives it mass and acts as either a guide rod for the recoil spring or as a point of contact for the forward mounted non reciprocating cocking handle assembly, so given the lack of this “bar” that perhaps explains the increased bulk of the Swiss guns bolt/carrier in relation to the German ones presumably they weigh similar in regards the resistance of there respective recoil springs in the same calibre.

    This “loose weight” i.e. The bolt carrier provides the “umph” when in set into a rearward motion by the recoil forces generated upon firing.

    I really like this gun, that trigger is fab amongst other things…

    Good job I watched the Gerat videos and this or I would possibly never have been struck by the notion in my amateurish attempts to design firearms on paper that said forces generated by firing could actually unlock the bolt by themselves if so desired by the appropriate design seems obvious almost now after numerous viewings ha.

    The Stgw57 presumably utilises a fluted chamber also, perhaps four flat rods set to overlap each others ends in a diamond shape:
    \/ could be pinned together so they could swivel in the middle and then to each other at either end to a bolt section at the front “top of the diamond” and a weight to it’s rear in the same manner so as to permit movement of the rods whilst attached to the peices aforementioned.

    The pins which would hold the four rods together in the middle “of the diamond” could be fitted with rollers at either end giving four vertical rollers in a H type shape if it’s central – part is the rods laying horizontally, these rollers could fit into recesses resembling a [] shape.

    A recoil spring would sit behind the weight in a tubular receiver, and the rollers would sit flush behind the upper and lower protrusions of the [ shape. Now upon firing, via a offset hammer/pin arrangement as per the video. Recoil would act upon the weight compressing the spring and retracting the rods inwards via the swivel pins, the rollers would now fit into the gap between the recesses and the entire diamond piece would move rearward in it’s contracted form kept in place via the shape of the recesses sides.

  • Ian

    That bounce effect generated by the bolt coming to an abrupt halt when it comes into contact with the barrel causing the carrier behind to “judder” rearwards, is replicated by recoil on firing initially in semi auto isn’t it i.e. when the bolt is fully forward. That’s how it is a delayed blowback, because the carrier isn’t locked only pushed forward under spring pressure when the spring is compressed the carrier allows the rollers to disengage from the recesses and the rearward motion generated by firing pushes the carrier back.

  • Ian

    So if the distance was extended, between the carrier and the bolt perhaps the delay between the rollers becoming disengaged from the recesses would be lengthened sufficiently to remove the need for a fluted chamber.

  • jdeleur

    How many of these rifles were sold to chili?

  • Mark F

    How many PE 57′s were imported to the US? Thanks

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