Inside a "Sniper" Rifle: SIG SG 550 Field Strip and Review of Internals

Published on January 9, 2020
Duration: 12:41

This video provides a detailed field strip and internal review of the SIG SG 550 "Sniper" rifle, highlighting its similarities to the SIG 553 and focusing on its larger gas system. The presenter explains the trigger mechanism's redesign for enhanced accuracy, utilizing an extension spring instead of a torsion spring for a lighter pull. The video also touches on the rifle's bull barrel and long-stroke piston operation, concluding with a brief look at a Valmet M78-83S as a bonus segment.

Quick Summary

The SIG SG 550 "Sniper" rifle features a redesigned trigger mechanism using an extension spring for a lighter pull, enhancing accuracy for police snipers. It operates on a long-stroke piston system with a larger gas system than the SIG 553, and includes rubber seals on the bolt to keep the action clean.

Chapters

  1. 00:00Introduction & Series Overview
  2. 00:49Removing Optic and Bipod
  3. 01:55Takedown Pin Mechanism
  4. 02:43Upper and Lower Receiver Separation
  5. 02:50Trigger Mechanism Deep Dive
  6. 03:23Safety Selector Function
  7. 03:53Trigger Redesign for Accuracy
  8. 06:37Gas System and Barrel Overview
  9. 06:58Recoil Spring and Piston Assembly
  10. 07:32Bolt Rotation and Action
  11. 07:45Bolt Action Seals
  12. 07:53Charging Handle Release
  13. 08:06Charging Handle Removal
  14. 08:11Charging Handle Linkage
  15. 08:21Long Stroke Piston System
  16. 08:24Bolt Carrier Group Inspection
  17. 08:43AK Similarities
  18. 08:53Piston Removal
  19. 09:19Reassembly Note & Bonus Gun Intro
  20. 09:33Bonus Gun: Valmet M78-83S
  21. 10:04Valmet M78-83S Background
  22. 10:37Valmet M78-83S Features
  23. 10:57Receiver Markings
  24. 11:04Valmet Legality in Canada
  25. 11:13Valmet M78-83S Variants
  26. 11:37Arnold Schwarzenegger Anecdote
  27. 12:04Bonus Gun Conclusion
  28. 12:07Outro & Patreon Support

Frequently Asked Questions

What are the main internal differences between the SIG SG 550 "Sniper" and the SIG 553?

The primary internal difference highlighted is the SIG SG 550 "Sniper" rifle's larger gas system. Otherwise, the field stripping and many internal components are very similar, making the process comparable between the two models.

Why was the trigger mechanism redesigned for the SIG SG 550 "Sniper"?

The trigger was redesigned to enhance accuracy for police sniper applications. It uses an extension spring instead of a torsion spring, resulting in a significantly lighter and more controllable pull, allowing for greater precision.

What type of operating system does the SIG SG 550 "Sniper" rifle use?

The SIG SG 550 "Sniper" rifle utilizes a long-stroke piston operating system. The recoil spring assembly is efficiently contained around the piston itself.

What is the purpose of the rubber lips on the bolt of the SIG SG 550?

The rubber lips on the bolt serve as seals. Their function is to prevent dirt, debris, and other contaminants from entering the action and getting behind the bolt, helping to maintain reliability.

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