Mud Test: Sig MCX Spear - US Army NGSW

Published on May 20, 2022
Duration: 9:23

The Sig MCX Spear, chosen by the US Army for its NGSW program, was subjected to an extreme mud test. While performing flawlessly with the dust cover closed, the rifle experienced significant failures to feed, fire, and eject when mud was introduced directly into the action with the dust cover open. This highlights a potential vulnerability in piston-driven systems compared to DI systems in extremely dirty conditions.

Quick Summary

The Sig MCX Spear, chambered in 6.8x51mm (.277 Fury), performed well in a mud test with its dust cover closed. However, when mud entered the action with the dust cover open, the rifle experienced immediate failures to feed, fire, and eject, highlighting potential vulnerabilities in piston systems.

Chapters

  1. 00:00Introduction & Baseline Check
  2. 00:44Closed Dust Cover Mud Test
  3. 01:46Open Dust Cover Mud Test & Failures
  4. 02:23Persistent Failures & Clearing Attempts
  5. 05:25Piston vs. DI System Analysis
  6. 06:39Adverse Gas Setting Test & Conclusion

Frequently Asked Questions

How did the Sig MCX Spear perform in a mud test with its dust cover closed?

When the dust cover was closed during the mud test, the Sig MCX Spear fired five rounds without any issues. This demonstrated the effectiveness of the dust cover in protecting the rifle's action from external debris.

What happened when mud was introduced directly into the Sig MCX Spear's action with the dust cover open?

With the dust cover open, the Sig MCX Spear immediately experienced a failure to feed upon firing. Subsequent attempts to clear the rifle and fire clean magazines resulted in persistent failures to fire and eject.

Why might piston-driven systems like the MCX Spear be more susceptible to mud than DI systems?

Piston-driven systems can struggle more in mud because they don't have the same self-cleaning effect as Direct Impingement (DI) systems. DI systems vent gas and debris out the ejection port, whereas piston systems can trap contaminants within the action.

Did the adverse gas setting improve the Sig MCX Spear's performance in the mud test?

No, switching the Sig MCX Spear to its 'adverse' gas setting did not resolve the malfunctions. The issues persisted, indicating that the mud had likely compromised the fire control group and locking mechanism.

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