Five More AR Builder Mistakes

Published on April 10, 2024
Duration: 14:34

This guide details common AR-15/AR-10 build mistakes and their solutions, as explained by Steve and Caleb from Brownells. Key areas covered include preventing accessory screw interference with the gas block, ensuring proper gas block alignment, adhering to the 40 ft-lbs torque spec for castle nuts, avoiding over-lapping upper receivers during lapping, and correct buffer tube installation depth. Following these steps ensures reliable function and accuracy.

Quick Summary

Learn 5 common AR-15/AR-10 builder mistakes from Brownells experts: accessory screw interference with the gas block, improper gas block alignment, overtorquing the castle nut (spec is 40 ft-lbs), excessive upper receiver lapping, and incorrect buffer tube depth.

Chapters

  1. 00:00Introduction
  2. 00:42Mistake 1: Accessory Interference
  3. 03:42Mistake 2: Gas Block Alignment
  4. 07:06Mistake 3: Castle Nut Torque
  5. 08:49Mistake 4: Upper Receiver Lapping
  6. 11:42Mistake 5: Buffer Tube Depth

Frequently Asked Questions

What are common AR-15 builder mistakes related to accessories?

A frequent mistake is using accessory screws that are too long, causing them to contact the gas block. This interference can disrupt barrel harmonics and negatively affect rifle accuracy. The solution is to shorten the screws or reposition the accessory.

Why is proper gas block alignment crucial for an AR-15?

Improper gas block alignment, whether rotational or fore/aft, can lead to rapid cycling failures. Carbon buildup can quickly obstruct the gas port if it's not perfectly centered, preventing the rifle from functioning reliably.

What is the correct torque for an AR-15 castle nut?

The recommended torque for an AR-15 castle nut is 40 ft-lbs. Overtorquing can damage the receiver extension threads and the end plate's alignment tooth, compromising the buffer tube's stability.

How can over-lapping an AR-15 upper receiver cause problems?

Excessive material removal during upper receiver lapping can cause the barrel to seat too deeply. This can lead to issues with the feed ramp alignment and the cam pin timing, potentially causing feeding failures.

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