Do It All Rifle Griffin MK2...BUT Something Happened.

Published on January 16, 2025
Duration: 17:04

This video details the process of diagnosing and rectifying severe overgassing issues in a 14.5-inch AR-15, specifically the Griffin Armament MK2. The presenter, drawing on experience from building numerous rifles, identifies an oversized gas port as the primary culprit after experiencing ejection problems, cycling failures, and accelerated wear. The guide includes using pin gauges to measure the gas port and recommends replacing the barrel if the port is found to be too large, emphasizing the importance of correct gas system tuning for optimal rifle performance.

Quick Summary

Diagnosing overgassing in an AR-15 involves observing brass ejection patterns and checking for cycling issues. An oversized gas port, typically above 0.075 inches for a 14.5-inch mid-length barrel, is the common cause. Accurate measurement with a pin gauge set is essential, and if the port is too large, replacing the barrel is often the solution.

Chapters

  1. 00:00Introduction: The 'Do-It-All' Rifle Concept
  2. 00:30Griffin MK2 Build Overview
  3. 01:39Sponsorships & Ammunition Choice
  4. 02:09Initial Range Testing & Problems
  5. 03:23Overgassing Symptoms: Brass Ejection
  6. 03:51Cycling Issues: Failure to Lock Back
  7. 04:31Post-Range Inspection: Fouling & Wear
  8. 05:05Return to Griffin for Warranty Work
  9. 05:15Post-Warranty Testing & Accuracy
  10. 05:37Persistent Overgassing Noted
  11. 05:46DIY Diagnosis: Gas Port Measurement
  12. 06:23Measuring the Gas Port
  13. 07:16Gas Port Size: 0.085 Inches
  14. 07:37Recommended Gas Port Sizes
  15. 08:14Barrel Swap Test: Rosco Barrel
  16. 09:05Testing with Rosco Barrel: Ejection Pattern
  17. 09:44Comparison: Original vs. Rosco Barrel
  18. 09:55Rail System Criticism: Anti-Rotation
  19. 10:37Positive Aspects of the Griffin MK2
  20. 11:12Griffin Suppressors & Muzzle Devices
  21. 11:30Lower Receiver Features
  22. 11:44Included Furniture & Options
  23. 12:05Rail M-LOK & Picatinny
  24. 12:10Weight & Overall Feel
  25. 13:17Rifle Setup: Maximizing 5.56 Capability
  26. 13:36Optic Choices: Vortex 3-15x & Leupold 2-10x
  27. 14:05Offset Optic Mount & Red Dot
  28. 14:24Light System: Streamlight Protac HLX
  29. 14:41Backup Iron Sights & Case
  30. 14:49Worn Skyline Light Bipods
  31. 15:20Griffin Dual Lock 7 Suppressor
  32. 15:29Conclusion: Is it a Do-It-All Rifle?
  33. 15:57Future Plans for the Griffin MK2
  34. 16:11Personal Experience with Problem Rifles
  35. 16:29Follow-Up Information
  36. 16:46Call to Action & Outro

Frequently Asked Questions

What are the common symptoms of an overgassed AR-15 rifle?

An overgassed AR-15 will typically eject brass forcefully and directly towards the target. Other signs include failures to lock back on the last round, magazines jamming due to excessive bolt speed, and accelerated wear on internal components like bolt lugs.

How can you accurately measure the gas port size on an AR-15 barrel?

The most accurate method is to use a pin gauge set. After disassembling the rifle, insert progressively larger pin gauges into the gas port until you find the largest one that fits snugly, or the smallest one that is loose. This measurement is crucial for diagnosing overgassing.

What is the recommended gas port size for a 14.5-inch AR-15 with a mid-length gas system?

For a 14.5-inch barrel with a mid-length gas system, a gas port size typically ranges from 0.070 to 0.075 inches. A size of 0.085 inches, as found in this video, is considered significantly too large and will cause overgassing issues.

What are the benefits of using a variable power optic over a red dot for a 5.56 rifle intended for longer ranges?

Variable power optics (like 3-15x or 2-10x) offer better magnification for identifying targets at extended distances (650+ yards), provide a superior eyebox for easier aiming, and include parallax adjustment for precise shooting, which red dots lack.

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