2nd Look: BRN-180 in 7.62x39

Published on August 8, 2022
Duration: 10:41

This video details the ongoing troubleshooting process with a Brownells BRN-180 upper receiver in 7.62x39. The primary issue encountered is the bolt locking back on the bolt catch instead of the magazine, occurring across multiple lower receivers. The reviewer also notes occasional magazine over-seating with specific lower receivers.

Quick Summary

The Brownells BRN-180 upper receiver in 7.62x39 has exhibited a recurring bolt lock-back issue, where the bolt catches prematurely on the bolt catch rather than the magazine. This problem has been observed across multiple AR-15 lower receivers, though it ran flawlessly on a Sons of Liberty Gun Works lower.

Chapters

  1. 00:06Introduction to BRN-180 7.62x39 Update
  2. 00:17Initial Range Outings & Variable Isolation
  3. 00:31Hammer Spring Importance for 7.62x39
  4. 00:53Bolt Locking Back on Bolt Catch Issue
  5. 02:33Testing Multiple Lower Receivers
  6. 04:13Third Trip: Testing with Various Lowers
  7. 05:39Suppressed vs. Unsuppressed Shooting & Bolt Catch Issue
  8. 06:34Magazine Over-Seating with Sugar Weasel Lower
  9. 07:14Testing Radical Firearms 7.62x39 Pistol Lower
  10. 08:32Summary of Issues and What It Means
  11. 08:39Brownells and PWS Support
  12. 09:02Flawless Operation on Sons of Liberty Gun Works Lower
  13. 09:37Potential Upper Receiver Specific Issue
  14. 09:40Brownells Sending Replacement Upper and Mags
  15. 10:09Future Testing and Conclusion

Frequently Asked Questions

What is the main reliability issue encountered with the Brownells BRN-180 upper in 7.62x39?

The primary issue is the bolt consistently locking back on the bolt catch instead of the magazine. This problem has been observed across multiple different AR-15 lower receivers tested with the upper.

What factors are important for reliable ignition with 7.62x39 in an AR-15 platform?

Reliable ignition with 7.62x39 often requires an extra power hammer spring. This is due to the use of hard military primers common in this ammunition, which standard springs may struggle to ignite consistently.

Which AR-15 lower receiver proved most compatible with the BRN-180 7.62x39 upper?

During the testing period, the Sons of Liberty Gun Works lower receiver was the only one that allowed the BRN-180 upper to function flawlessly without encountering the bolt lock-back issue.

Are there any magazine seating issues reported with the BRN-180 7.62x39 upper?

Yes, occasional magazine over-seating has been noted. This occurred with the BRN-180 upper on a Sugar Weasel lower receiver and also on a KE Arms KP15 polymer lower.

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