Quick Tip: How to Quickly Assess an AR-15

Published on April 14, 2025
Duration: 13:59

This guide provides a quick external assessment of an AR-15 for potential buyers, focusing on common issues that indicate builder inexperience or potential problems. Key checks include magazine catch alignment, castle nut security, buffer tube orientation, gas tube installation, and muzzle device tightness. The assessment is designed to be performed without disassembling the firearm, making it suitable for gun shows or shop environments.

Quick Summary

When assessing an AR-15, focus on external checks like magazine catch button flushness, castle nut tightness and orientation, buffer tube alignment, and gas tube installation. These indicators can reveal builder inexperience and potential assembly flaws without needing to disassemble the firearm.

Chapters

  1. 00:08Introduction to AR-15 Quick Assessment
  2. 01:01Visual Inspection Basics
  3. 01:46Magazine Catch Button Check
  4. 02:26Castle Nut Inspection
  5. 03:08Buffer Tube Alignment
  6. 03:28Grip and Take Down Pin Check
  7. 04:00Ejection Port Cover Check
  8. 04:20Bolt Carrier Group Visual
  9. 04:32Handguard Alignment and Bolts
  10. 05:00Barrel and Gas Tube Inspection
  11. 05:34Gas Block Set Screw Check
  12. 05:50Gas Block Alignment Check
  13. 06:23Muzzle Device and Crush Washer
  14. 07:09Selector Lever and Mag Release
  15. 07:33Upper/Lower Receiver Play and Stock
  16. 07:37Optic Mounting Check
  17. 08:08Bonus: Internal Checks (Trigger)
  18. 08:19Bolt Catch Check
  19. 09:25Buffer Retainer Check
  20. 09:58Trigger Guard Inspection
  21. 10:05Upper Receiver and Bolt Carrier Group (BCG)
  22. 10:25Gas Key Staking
  23. 11:21Charging Handle and Gas Tube Protrusion
  24. 12:06Feed Ramp Alignment
  25. 13:12Conclusion and Final Tips

Frequently Asked Questions

What are the most critical external checks for a used AR-15?

Key external checks for a used AR-15 include ensuring the magazine catch button is flush, the castle nut is tight and correctly oriented, the buffer tube is aligned, and the gas tube is installed properly without being upside down. These indicate builder competence and potential issues.

How can I tell if an AR-15 was poorly assembled without taking it apart?

Look for common assembly flaws like a magazine catch screw that's too deep or too proud, a loose castle nut, an angled buffer tube, or a gas tube installed upside down. These are often visible externally and suggest inexperience.

What is a common mistake with AR-15 gas tubes?

A frequent mistake is installing the gas tube upside down. It should curve upward from the gas block into the receiver. An upside-down tube will be forced to bend into the upper receiver, causing significant problems.

Why is feed ramp alignment important on an AR-15?

Proper feed ramp alignment between the barrel extension and the upper receiver ensures smooth feeding of ammunition. Misalignment can cause the bullet nose to catch on the ramps, leading to feeding failures and malfunctions.

More Training & Techniques Videos You Might Like

More from Brownells, Inc.

View all →