The SIG SG 550 rear sight adjustment tools feature in two Swiss Army Knives, the Wenger STGW 90 and the Victorinox FASS 90 models, also known as the Korrekturmessers (Correction Knives). These models and tools were commissioned by the Swiss Grunig + Elmiger hunting and shooting sports equipment company, and their logo, a stylised GE, appears on the scales of these models.
These Swiss Army Knives contain two tools for adjusting the diopter rear sight drum on the rifle.

• The windage (left/right) sight adjustment tool - Which is a rounded ‘screwdriver’ built into the frame of the knife (using one of the SAK springs)
  • Used for screw 4 on the linked diagram above
  • The Victorinox and Wenger tools are very similar
• The elevation (up/down) sight adjustment tool – Which is a very small, fold-out, flat screwdriver inside a sprung cylinder
  • Used for screw 2 on the linked diagram above
    

    Windage Adjustment Tool

    
    

    

    Victorinox Elevation Adjustment Tool - Opened

    
    
  • The cylinder is used to align with, and keep the screwdriver on, the adjustment screw
  • The Victorinox and Wenger tools are slightly different - See the images below

Key to the markings:

The markings on the scales inform the user which way to turn the screw to make the required adjustment

• B – Bei (To the) ...... - ie If your shots are to the / too ...... then turn in the direction of the arrow to correct
• L – Links (Left)
• R – Recht (Right)
• T – Tiefe (Deep/Low)
• H – Höhe (High)

See the STGW sight adjustment instructions image here.

Glossary

There are several terms and abbreviations associated with these tools - Here are some definitions:

• FASS - Fusil d'assaut (French) / Fucile d'assalto (Italian) = Assault Rifle
• SG / STG / STGW - Sturmgewehr = Assault rifle in German
• SIG - Schweizerische Industrie Gesellschaft, the Swiss company that makes the SG 550, now known as SIG Sauer AG
• SG 550 / STGW 90 / FASS 90 - An assault rifle made by SIG

External References

• Using the sight adjustment tool: YouTube video - Victorinox Korrekturmesser für STGW 90.
• MultiTool.org thread on the FASS 90

Wenger Elevation Adjustment Tool

Victorinox Elevation Adjustment Tool