Quick Tip: BRN-4/HK-416 Barrel Swap

Published on March 8, 2024
Duration: 14:05

This video provides a detailed, step-by-step guide on how to swap barrels on a Brownells BRN-4 upper receiver, which is an HK-416 clone. It covers the necessary tools, the process of removing the old barrel and gas block, installing the new barrel, and reassembling the piston system. The guide emphasizes using specific tools like an HK barrel nut wrench and proper torque specifications for reassembly.

Quick Summary

To swap barrels on a BRN-4 (HK-416 clone) upper receiver, you'll need specific tools like an HK barrel nut wrench and a torque wrench. The process involves removing the piston assembly, barrel nut, and gas block roll pins. The new barrel is installed, the barrel nut torqued to 45 ft-lbs, and the gas block and piston assembly are reinstalled.

Chapters

  1. 00:00Introduction and Overview
  2. 00:04What is the BRN-4?
  3. 00:25Reason for Barrel Swap
  4. 00:51Barrel Length Compatibility Notes
  5. 01:19Tools Required
  6. 02:23Disassembly: BCG and Charging Handle
  7. 02:51Disassembly: Piston Assembly
  8. 03:12Disassembly: Barrel Nut
  9. 04:26Disassembly: Gas Block Roll Pins
  10. 05:01Removing the Gas Block
  11. 06:07Installing New Barrel and Barrel Nut
  12. 06:29Torquing the Barrel Nut
  13. 06:44Reinstalling Gas Block
  14. 07:10Reinstalling Piston Assembly
  15. 07:30Handguard Fitment Examples
  16. 08:15Installing Handguard
  17. 13:17Final Steps and Conclusion

Frequently Asked Questions

What is the BRN-4 upper receiver?

The BRN-4 upper receiver is Brownells' clone of the HK-416, offering a similar platform for firearm enthusiasts. It is compatible with standard AR-15 lower receivers.

What are the key tools needed for a BRN-4 barrel swap?

Essential tools include a vise, an upper receiver fixture, an HK barrel nut wrench, a torque wrench, a roll pin punch (size 6 recommended), a bench block, and a hammer for removing the gas block roll pins.

What is the correct torque specification for the BRN-4 barrel nut?

The barrel nut for the BRN-4 should be torqued to approximately 45 foot-pounds. It's crucial to use a torque wrench for accurate and safe assembly.

Can I use any barrel length with any BRN-4 upper receiver?

No, for a 13.7-inch barrel, you must use a 14.5-inch or 16-inch BRN-4 upper. The 10.3-inch upper has a different piston block that won't regulate correctly with this barrel length.

How is the gas block removed and reinstalled on a BRN-4?

The gas block is removed by knocking out two roll pins with a punch, bench block, and hammer, allowing it to slide off. Reinstallation involves sliding it back on and reinserting the roll pins.

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