AR15 Upper Receiver Visual Checks/Inspections

Published on December 10, 2021
Duration: 6:02

This guide details essential visual inspections for AR-15 upper receivers, focusing on identifying manufacturing defects without specialized gauges. Key areas include feed ramp integrity, bolt carrier group movement, receiver symmetry, gas tube hole concentricity, barrel extension threads, and the presence of cracks. Proper inspection helps ensure reliable firearm function and longevity.

Quick Summary

Perform visual inspections on AR-15 upper receivers by checking feed ramps for complete milling, ensuring the bolt carrier group moves freely, examining receiver symmetry, and looking for cracks. Avoid modifying feed ramps with tools, as this can compromise durability and lead to future feeding issues.

Chapters

  1. 00:00Introduction to Visual Inspection
  2. 00:33Inspecting Feed Ramps
  3. 01:49Bolt Carrier Group Fit Check
  4. 02:37Checking Receiver Symmetry
  5. 03:15Gas Tube Hole Alignment
  6. 04:04Barrel Extension Thread Inspection
  7. 04:28Detecting Cracks in Upper Receiver
  8. 05:14Comparing Receiver Wall Thickness
  9. 05:33Visualizing Off-Center Defects
  10. 05:52Conclusion and Takeaways

Frequently Asked Questions

What are the key visual checks for an AR-15 upper receiver?

Essential visual checks include inspecting feed ramps for proper milling, ensuring the bolt carrier group moves freely, examining receiver symmetry, checking gas tube hole concentricity, looking at barrel extension threads, and searching for any cracks within the receiver.

Can I fix improperly milled feed ramps on an AR-15 upper receiver?

While you can physically alter feed ramps with tools, it's generally not recommended. Removing anodizing reduces hardness and wear resistance, potentially leading to future feeding problems. It's better to identify and reject uppers with improperly milled ramps.

What causes a bolt carrier group to bind in an AR-15 upper receiver?

Binding of the bolt carrier group, often felt when it's about three-quarters of the way forward, can be caused by areas within the upper receiver's rails being crushed or improperly machined, creating a tight spot.

Why is receiver symmetry important for an AR-15 upper?

Receiver symmetry, particularly the concentricity of the main bore and gas tube hole, ensures proper alignment of the barrel and gas system. Significant misalignment can necessitate a larger gas port for reliable cycling.

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