S-550 Series is a Swiss made Assault Rifle designed in 1970s in order to replace the SG510 Rifle used by Swiss Army as the new standard service rifle. After a long term test between serval choice with a suitable cartridges, Swiss army decided to choose SG 541 rifle, which renamed as Stgw 90 as offical name, was accepted into service in 1990, over 600000 rifles have been delivered since then and production for the army has ceased.

S-551 is the export version of the Stgw 90 rifle in carbine size which has a short pattern barrel (14.3 inch), gas tube and piston, designed for security and special forces.

Features:
- Green Gas powered
- Comes with Steel upper receiver with 20mm top rail
- Comes with Steel lower receiver
- Comes with Alloy handguard
- Comes with Alloy outer barrel with flash hider
- Comes with Metal flip-up front and rear sight
- Comes with Polymer folding stock
- Comes with Polymer non-slip pistol grip
- Comes with Metal bolt and charging handle
- Comes with Steel trigger, ambi selector, ambi magazine release and bolt release
- Package includes Metal 32 rounds gas magazine

Specifications:
Length: 850mm / 610mm (Total Length)
Weight: 3520g (with magazine)
Color: Black
Material: Steel , Metal, Polymer
Hop-up: Adjustable
Shooting Mode: Safety , Semi-Auto , Full-Auto
Magazine Capacity: 32 Rounds
Bullet Type: 6mm BB
Gas: 12KG (Green Gas)
Power(Muzzle Velocity): 350 FPS (0.2g BB, Green Gas)
Manufacturer: GHK