Sig MPX SBR 9mm Caliber Carbine

Published on August 11, 2018
Duration: 18:26

This video provides an in-depth technical examination of the Sig MPX SBR 9mm carbine, focusing on its mechanical operation and design improvements over previous generations. The presenter, with expertise in firearm mechanics, highlights the MPX's locked breech system, short-stroke piston operation, and ambidextrous controls. Key Gen 2 features like multi-caliber capability (9mm, .357 SIG, .40 S&W) and improved magazine design are discussed, along with internal enhancements addressing durability issues found in blowback 9mm submachine guns.

Quick Summary

The Sig MPX SBR 9mm carbine features a Gen 2 design with a locked breech, short-stroke piston system, and multi-caliber capability for 9mm, .357 SIG, and .40 S&W. Internal enhancements address durability issues, and it boasts ambidextrous controls for enhanced usability.

Chapters

  1. 00:04Introduction & Channel Focus
  2. 00:48Sig MPX SBR Model Overview
  3. 01:25Designers & Program Leaders
  4. 01:56Gen 1 vs. Gen 2 Features
  5. 02:00External Controls & Features
  6. 02:47Identifying Gen 1 vs. Gen 2
  7. 03:02KeyMod Handguard & Multi-Caliber
  8. 03:15Gen 2 Magazine Compatibility
  9. 03:29Backup Sights & Charging Handle
  10. 03:50Internal Mechanics: Receiver
  11. 03:55Disconnector Durability Improvements
  12. 04:44Hammer Frame Durability
  13. 05:059mm vs. 5.56 Operating Principles
  14. 05:20Bolt Buffer & Receiver Extension
  15. 05:39Stock Assembly & Interchangeability
  16. 06:04Operating Mechanism: Bolt Carrier Group
  17. 06:13Locked Breech vs. Direct Blowback
  18. 06:31Safety & Pressure Benefits
  19. 06:43Cam Pin & Dual Recoil Springs
  20. 07:05Lower Handguard Removal
  21. 07:16Barrel Removal & Piston System
  22. 07:25Short-Stroke Piston Operation
  23. 07:46Fixed Extractor Design
  24. 08:09Multi-Caliber Barrels: Availability
  25. 09:01Personal Purchase & Tax Stamp
  26. 09:15Reliability & Robustness
  27. 09:23Market Application: US vs. International
  28. 09:55Well Thought Out System
  29. 10:11Test Firing & Reliability
  30. 10:40Bolt Over-Travel Improvements
  31. 10:49Colt M16 Bolt Carrier Comparison
  32. 11:39Problems with Bolt Over-Travel
  33. 12:04Trigger Compartment Visibility
  34. 12:31Magazine Design & Features
  35. 13:01Latest Submachine Gun Technology
  36. 13:39Ambidextrous Controls Recap
  37. 13:52Steel Pins for Charging Handle Durability
  38. 14:12Gen 1 vs. Gen 2 Magazines
  39. 14:38Ammunition Provided by Black Hills
  40. 15:39Magazine Loading Ease
  41. 17:29Overall Impressions & Durability
  42. 17:47M16/M4 Feel & Enhancements
  43. 17:55Sig's Market Responsiveness
  44. 18:03Impressed Firearms
  45. 18:11Personal Purchase Decision

Frequently Asked Questions

What are the key differences between Gen 1 and Gen 2 Sig MPX models?

The primary distinction is the Gen 2's multi-caliber capability, allowing it to fire 9mm, .357 SIG, and .40 S&W with the same receiver and magazines. Gen 2 also features a KeyMod handguard and internal improvements for enhanced durability, particularly addressing disconnector and hammer frame issues.

How does the Sig MPX operating system differ from traditional 9mm SMGs?

Unlike the direct blowback system common in many 9mm submachine guns, the Sig MPX utilizes a locked breech system with a short-stroke gas piston. This design enhances reliability, safety, and the ability to handle higher pressure ammunition more effectively.

What internal improvements were made to the Sig MPX to increase durability?

Sig engineers addressed issues with the disconnector and hammer frames by redesigning the receiver. A shelf is built in to catch the hammer as it moves rearward, preventing it from striking and breaking the disconnector, a common failure point in older designs.

Is the Sig MPX truly multi-caliber, and are all barrel options available?

The Gen 2 Sig MPX is designed for multi-caliber use (9mm, .357 SIG, .40 S&W) with interchangeable barrels and magazines. However, Sig has not yet released barrels for .357 SIG and .40 S&W to the public, focusing primarily on the 9mm platform.

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