Quick Tip: AR-15 Gas Block Alignment

Published on December 2, 2020
Duration: 3:01

This guide, presented by a Brownells technical expert, details the proper installation and alignment of an AR-15 gas block. It emphasizes the importance of aligning the oversized gas block port with the barrel's gas port, discussing tolerances and the common practice of dimpling the barrel for set screw indexing. The expert recommends dimpling only the rear screw to accommodate variations between manufacturers.

Quick Summary

Proper AR-15 gas block alignment is crucial for preventing malfunctions. The gas block port is intentionally oversized to allow for slight misalignment. For installation, dimpling only the rear set screw location is recommended due to varying screw spacing between manufacturers. Both pushing the block against the barrel shoulder and leaving space for an end cap can work for alignment.

Chapters

  1. 00:00Introduction to Gas Block Alignment
  2. 00:22Gas Block Manufacturing and Port Size
  3. 00:52Visual Alignment and Tolerances
  4. 01:20Shoulder Alignment vs. End Caps
  5. 01:55Barrel Dimpling Best Practices
  6. 02:36Conclusion and Support

Frequently Asked Questions

What is the most common cause of malfunctions on an AR-15 platform related to gas blocks?

Misalignment of the gas block is a leading cause of malfunctions on the AR-15 platform. Proper alignment ensures the correct amount of gas is directed to cycle the bolt carrier group, preventing issues like short-stroking or failures to feed.

Why is the gas block port intentionally larger than the barrel's gas port?

The gas block port is intentionally drilled larger than the barrel's gas port to provide a tolerance for slight misalignment. This design allows for some room for error during installation without negatively impacting the firearm's function.

Should I dimple my AR-15 barrel when installing a gas block?

Dimpling the barrel for the set screws is recommended for precise alignment. However, it's best practice to only dimple the location for the rear set screw, as screw spacing can vary between different gas block manufacturers.

What's the difference between pushing a gas block against the barrel shoulder versus leaving space for an end cap?

Both methods can achieve proper gas block alignment. Pushing the block against the shoulder ensures it's seated firmly, while leaving space for an end cap is also a common practice. The key is ensuring the gas block's port is correctly aligned with the barrel's gas port.

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