Sons of Liberty Gunworks Lower Receiver Physical

Published on November 30, 2020
Duration: 14:27

This video provides a detailed physical inspection of a Sons of Liberty Gunworks lower receiver. It covers essential checks such as thread fitment, trigger pull weight, bolt catch function, pin hole tolerances, and carrier travel. The instructor demonstrates the use of various specialized tools for accurate measurements and highlights potential tolerance stacking issues.

Quick Summary

A Class 3 fit for a receiver extension (buffer tube) thread signifies the highest quality fit, meaning the threads engage smoothly with minimal play. It's the best fit achievable without requiring specialized tools for custom applications. A trigger pull weight of 6.5 pounds is considered good for a military-style trigger.

Chapters

  1. 00:01Introduction & Previous Repair
  2. 00:54Initial Inspection & Function Check
  3. 01:48Trigger Pull Weight Test
  4. 02:22Disassembly for Inspection
  5. 03:46Bolt Catch Function Test
  6. 04:18Pin Removal & Hole Gauging
  7. 05:13Magazine Catch Tool Demonstration
  8. 05:53Selector Board & Pivot/Take-Down Hole Check
  9. 06:46Buffer Assembly Inspection
  10. 07:30Carrier Assembly Travel Check
  11. 09:10Buffer Tube Opening & Engagement Check
  12. 09:33Reassembly Process
  13. 11:11Magazine Catch Reinstallation
  14. 12:17Final Magazine Well Gauge Test
  15. 13:06Cosmetic Touch-Up: Brass Marks
  16. 14:17Conclusion & Final Verdict

Frequently Asked Questions

What is a Class 3 fit for a receiver extension thread?

A Class 3 fit for a receiver extension (buffer tube) thread signifies the highest quality fit, meaning the threads engage smoothly with minimal play. It's the best fit achievable without requiring specialized tools for custom applications.

How can you test the bolt catch function on an AR-15 lower receiver?

To test the bolt catch, place an assembled bolt carrier group on the catch's tab. The spring should be strong enough to hold the weight of the carrier without collapsing, indicating proper function.

What is tolerance stacking and how does it affect AR-15 builds?

Tolerance stacking occurs when minor manufacturing variations in multiple components accumulate. In AR-15s, this can lead to issues like excessive bolt carrier travel, potentially causing the carrier key to hit the lower receiver.

What is the recommended tool for removing an AR-15 magazine catch?

While various methods exist, a specialized 'mag catch tool' is demonstrated as an effective and inexpensive device for easily removing and installing the AR-15 magazine catch. Other items like a Bic pen or even a steel punch can be used, though the latter may cause cosmetic damage.

How can cosmetic brass marks on AR-15 pins be fixed?

Cosmetic brass marks left on pins from using a brass punch can be touched up using Birchwood Casey Aluminum Black. Apply it to the affected areas and then flush it out to prevent any unseen corrosion.

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