SMOOTHEST 9mm Upper! MEAN Arms Bearing Delay

Published on March 25, 2024
Duration: 12:25

This video reviews the MEAN Arms bearing delay 9mm upper receiver, highlighting its lightweight design, polymer handguard, and innovative ball bearing delay system. The reviewer demonstrates its performance with various 9mm ammunition types, noting its smooth recoil, good accuracy, and excellent suppression. While generally reliable, minor bolt hold-open issues were observed with subsonic ammunition, potentially requiring buffer tuning.

Quick Summary

The MEAN Arms bearing delay 9mm upper receiver features a unique ball bearing system for reduced recoil and enhanced accuracy. Its design allows for excellent heat dissipation, enabling a lightweight polymer handguard. While generally reliable, it may require buffer tuning for consistent last-round bolt hold-open with subsonic ammunition.

Chapters

  1. 00:00Introduction & First Impressions
  2. 00:41MEAN Arms Bearing Delay Upper Overview
  3. 01:01Sponsor: Sonoran Desert Institute
  4. 01:24Optics & Suppressor Setup
  5. 01:51MEAN Arms Design Philosophy
  6. 02:21Bearing Delay System Explained
  7. 02:38Subsonic Ammunition Test
  8. 02:53Magazine Conversion System
  9. 03:29Compatibility with AR-15 Lowers
  10. 03:37Heat Dissipation & Polymer Handguard
  11. 04:06Subsonic Ammunition with Suppressor
  12. 04:44Full Power 147 Grain Ammunition Test
  13. 05:12Bolt Hold Open Observation (Subs)
  14. 05:28Full Power 124 Grain Ammunition Test
  15. 05:48Buffer Weight Discussion (H1)
  16. 06:21Gas to the Face Observation
  17. 06:36Bolt Travel & Bolt Hold Open Issues
  18. 06:57Thermal Performance Check
  19. 07:01Continued Shooting with 124 Grain
  20. 07:13Pistol vs. PCC Build Options
  21. 07:36Gideon Optics Review
  22. 08:05Supers Ammunition Test (Bellm)
  23. 08:10Steel Case Ammunition Test
  24. 08:33Fluted Chamber & Steel Case
  25. 09:25Thermal Performance with Steel Case
  26. 09:43Gas & Recoil Summary
  27. 10:02Overall Reliability & Accuracy
  28. 10:24Final Thoughts on MEAN Arms Upper
  29. 10:52Subsonic Lock to Rear Test (Retry)
  30. 11:25Successful Bolt Lock to Rear
  31. 11:35Conclusion & Thanks
  32. 11:53Upcoming Range Videos
  33. 12:07Final Thermal Check

Frequently Asked Questions

What is the primary advantage of the MEAN Arms bearing delay system in a 9mm upper?

The primary advantage of the MEAN Arms bearing delay system is its ability to significantly reduce recoil and improve accuracy by using ball bearings to delay the bolt's rearward movement. This system also contributes to excellent heat dissipation, allowing for lighter components like a polymer handguard.

How does the MEAN Arms 9mm upper handle magazine compatibility?

The MEAN Arms 9mm upper is designed to work with standard AR-15 lowers and 5.56 STANAG magazine wells. MEAN Arms also offers inserts that allow standard PMAGs to be converted for reliable feeding of 9mm ammunition, avoiding the need for proprietary magazines.

What were the observed reliability issues with the MEAN Arms 9mm upper?

The main reliability observation was an occasional failure to lock the bolt to the rear with subsonic 147-grain ammunition. This suggests the bolt may not be traveling far enough back, potentially requiring buffer tuning or a different buffer weight for optimal performance with lighter loads.

How does the heat management of the MEAN Arms upper compare to traditional designs?

The bearing delay system in the MEAN Arms upper excels at heat management by containing most of the heat within the chamber and bolt area. This allows for the use of a lightweight polymer handguard, as less heat transfers forward, even after extensive firing.

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