| SIG Stgw 57 |
SIG AM 55
In the 1950s, the famous Swiss company SIG (Schweizerische Industrie Gesellschaft) was developed AM automatic rifle cartridge 55 under Swiss GP11 (7.5h55 mm), which was used in the construction of the principle of delayed blowback recoil. Basis for the development of new weapons designer Rudolf Amsler served German Stg 45 assault rifle.
In 1957, after a little refinement new automatic rifle was adopted by the Swiss army under the designation Stgw 57 (Sturm Gewehr 57 - Assault rifle model 1957). The commercial market GUNS Stgw 57 Received designation SIG SG 510.
| SIG Stgw 57 |
assault rifle Stgw 57 uses the principle of delayed blowback recoil, consisting of two parts. Slowing down the shutter under the action of withdrawal by means of the impact roller.
Right in the slot receiver is a comfortable T-shaped cocking lever.
cocking weapons must pull back and release the T-handle, the shutter goes ahead dosylaya cartridge in the chamber. The hammer is cocked and held the sear. The shutter consists of two parts: a stem and larvae. The larva mounted rollers unusual design: on the actual cylindrical roller pivotally fastened small curly parts. When the cartridge enters the chamber, the larva stops and shutter stem continues to move and passes between the rollers. The mirror shutter has a tapered shape, and the rollers are displaced in the grooves of the receiver.
When fired cartridge cases moving backwards. The inner surface of the chamber has longitudinal grooves that enable the gunpowder gases pass to a mirror shutter. There are two openings through which the gases pass through the larva and put pressure on the stem of the valve. Pressure liner and propellant gases causes the rollers to move inwards along the inclined surface of the stem bolt. Due to the angles wedge surface stem bolt is forced to move back and detached from the larvae.
SIG Stgw 57
When the rollers out of the grooves, the shutter in a disconnected state, continues to roll back. Cartridge cases pressed against the mirror shutter ejector. He is pivotally mounted on the top of the combat larvae during the rollback gate rests on a sloping ledge on the left side of the receiver, as a result of the sleeve is thrown through the window on the right side of the receiver. Such a design provides a smoother operation of the mechanism during the ejection.
trigger mechanism has a simple design and unlike most modern rifles of that period, was not borrowed from the model M1 «Garand». It uses the sear with cutout for the pivot and spring constant action. The trigger is a stamped piece with the tab in the rear. Clicking on it raises the rear of the projection whispered while whispering tooth emerges from the notch in the trigger, and the trigger has a drummer. In single mode, the sear under the action of the fire spring is moving forward and out of engagement with the trigger projection. When the trigger moves back, he engages the sear cut. It is under the influence of a spring trigger moves back until it stops. The next shot can be made only after pressing the trigger, as the sear is released only when moving forward hook. Thereafter, the process is repeated, with the proviso that the stem with the shutter striker in the closed position.
With continuous fire projection trigger rises much higher and causes tooth whispered to go further, causing the trigger when reversing captured not trigger sear, and safety, and is held in position until the rear until the rear of the shutter does not make Rollers go into the recesses. Thus, shooting can be resumed at the fully closed gate, which is another safety device. When installing an interpreter ceasefire to "fuse" the trigger is locked in the down position. While firing trigger produces a blow to the L-shaped hinge arm, which, in turn, has a drummer.
| SIG SG 510-1 |
«Arctic» trigger intended for firing thick gloves, permanently installed and is also used when firing rifle grenades. Under normal conditions, is folded along the receiver.
Receiver Stgw 57 made by stamping and reinforced in the back for mounting the stock and organize the return spring. In front of the breech of the barrel is attached and posted the guide rollers, which can be replaced when wear.
| SIG SG 510-1 || SIG SG 510-4 |
| Caliber, mm || 7.5x55 || 7.62x51 |
| Length mm || 1100 || 1015 |
| Barrel length, mm || 583 || 505 |
| Weight || 5.7 || 4.37 |
| Shop, |
| 24 || 20 |
| Start |
Bullets, m / s
| 720 || 790 |
| Effective |
| 640 || 600 |
| Rate of fire, |
Rds / min
| 550 - 600 |
barrel is made by cold forging and is equipped with a muzzle brake, which also serves as a flame arrester.
At the front end
barrel rings are serving as guides for firing rifle grenades. Shooting a rifle grenade made using blank cartridges, while instead of the standard set special store.
Under the barrel provided for mounting a bayonet-knife.
trunk nestled perforated casing, which can be mounted folding bipod. Folding bipod unfolded can be mounted in two positions - under the muzzle of the barrel or close to the receiver.
cylindrical diopter sight and front sight mounted on folding racks sight drum is provided with fixed settings. Necessary range can be set by clicking noises. Fly can move left and right, up and down with a special key. Also automatic rifles Stgw. 57 could be equipped with optical or night sights.
Food weapons carried out regular box-detachable magazine capacity of 24 cartridges.
rifle has a fixed buttstock made of plastic with integrated recoil buffer.
weapons equipped with a handle for carrying the rifle.
| SIG SG 510-2 |
Stgw 57 assault rifle was produced in several versions:
- SG 510-1 - basic model Stgw 57;
- SG 510-2 - lightweight version of the SIG SG 510-1;
- SG 510-3 - chambered caliber 7,62 x39 mm Soviet-made, designed for competition on a new machine for the Finnish army and produced a small series;
- SG 510-4 - chambered for 7,62 x51 mm NATO with a more ergonomic grip and fore-end, a modified form of the butt, and new iron sights.
"military" option SIG SG 510-4, except chambered caliber 7,62 x51 mm NATO had a slightly shorter barrel and smaller mass. Curved instead of the original stores in 24 cartridges used in direct stores in 20 rounds. Butt and fore-end made of wood.
| SIG SG 510-3 |
assault rifle SIG SG 510-4 delivered to the armed forces of Chile and Bolivia, and civilian semiautomatic version SIG SG 510 were supplied to the domestic market of Switzerland, as well as for export.
Especially for the civilian market weapons issued semiautomatic version SIG SG 510:
- SIG PE-57 - designed for the Swiss market and is a variant Stgw. 57 without the possibility of firing bursts;
- SIG AMT (American Match Target) - intended primarily for export to the U.S. and is a modification of SIG SG 510-4 without the possibility of firing bursts and without bayonet mounts and rails for rifle grenades on the trunk. All SIG AMT supplied with brand fasteners for optical sights and had awkward open front and rear sights.
| SIG SG 510-4 |
were produced about 500,000 units of military options and about 7000 - Civil.
In general, weapons family SIG 510 has a very high reliability, excellent firing accuracy and ease of use. The main disadvantages of this series weapons were a significant mass of weapons and its exorbitant price.
In the 1980s most of the assault rifles Stgw 57 was withdrawn from service and replaced by newer models SIG 550 / Stgw 90.
| SIG AMT |