Tech Tip: BRN-9 Upper Disassembly, Maintenance & Reassembly

Published on May 18, 2023
Duration: 13:31

This guide details the field stripping, maintenance, and reassembly of the BRN-9 upper receiver. It covers removing the bolt assembly, charging handle, and firing pin, along with lubrication points and reassembly steps. The video emphasizes the unique internal buffer system of the BRN-9, which contains the recoil spring and weight within the upper receiver.

Quick Summary

The BRN-9 upper receiver features a unique internal buffer system containing a weight and recoil spring within the upper itself, eliminating the need for an external buffer tube. Disassembly involves removing the serrated back plate to access the bolt assembly, charging handle, and firing pin. Maintenance includes lubricating high-friction surfaces, and the recoil spring/buffer should be replaced around 5,000 rounds.

Chapters

  1. 00:04Introduction to BRN-9 Upper Maintenance
  2. 00:39Removing the Bolt Assembly
  3. 01:42Identifying Components: Recoil Spring, Guide, Buffer
  4. 02:03Removing the Recoil Spring
  5. 02:14Removing the Bolt Assembly
  6. 02:20Removing the Charging Handle
  7. 02:47Removing the Charging Handle Retaining Block
  8. 03:13Further Disassembly: Bolt Weight and Firing Pin
  9. 04:08Firing Pin Retention Mechanism
  10. 04:26Removing the Firing Pin
  11. 04:53General Maintenance and Lubrication Points
  12. 06:18Recoil Springs and Buffers: Lifespan and Replacement
  13. 07:06Reassembly: Firing Pin Installation
  14. 07:52Reassembly: Attaching Weight to Bolt
  15. 08:27Reassembly: Installing the Charging Handle
  16. 09:04Correct Installation of Retaining Block
  17. 10:08Consequences of Incorrect Retaining Block Installation
  18. 11:03Reassembly: Inserting the Bolt Assembly
  19. 11:28Reassembly: Installing the Recoil Spring
  20. 11:48Reassembly: Installing the Back Plate, Guide Rod, and Buffer
  21. 12:20Securing the Back Plate Assembly
  22. 12:40Final Assembly and Barrel Cleaning
  23. 13:09Conclusion and Contact Information

Frequently Asked Questions

How do you disassemble the BRN-9 upper receiver?

To disassemble the BRN-9 upper, first ensure it's clear. Remove the upper from the lower. Push the serrated back plate and slide it down to release the bolt assembly. Remove the back plate, guide rod, buffer, and recoil spring. Tilt to remove the bolt. The charging handle is removed by pulling it back and sliding it out.

What are the key components of the BRN-9's internal buffer system?

The BRN-9 features an internal buffer system within the upper receiver, consisting of a weight that attaches to the bolt carrier and a recoil spring. This design eliminates the need for an external buffer tube and spring assembly common in other AR-style PCCs.

How do you lubricate the BRN-9 upper receiver during maintenance?

During maintenance, apply a light coat of oil to high-friction surfaces on the BRN-9's bolt assembly, including the bolt, weight, and recoil spring. These areas are typically identifiable by wear marks on the stainless steel nitride coating.

When should the recoil spring and buffer be replaced on a BRN-9?

It's recommended to replace the recoil spring and buffer assembly on a BRN-9 approximately every 5,000 rounds. These are consumable parts that wear over time, and replacement ensures continued reliable function.

Related News

All News →

More Gunsmithing & DIY Videos You Might Like

More from Brownells, Inc.

View all →