What is a BUFFER TUBE?

Published on March 11, 2026
Duration: 1:30

This guide explains the function of the buffer tube in an AR-15 or AR-pattern rifle, as demonstrated by Jared from GUNBROS. The buffer tube is a critical component of the operating system, housing a buffer and spring. Upon firing, the bolt carrier group compresses this spring and buffer assembly as it moves rearward, and the subsequent expansion of the spring drives the BCG forward to chamber the next round. This process is essential for the semi-automatic function of AR-pattern firearms.

Quick Summary

The buffer tube on an AR-15 or AR-pattern rifle is a critical part of its operating system, attached to the lower receiver. It houses a buffer and spring that work with the bolt carrier group (BCG). When the rifle fires, the BCG moves back, compressing the spring and buffer, then the spring's expansion drives the BCG forward to chamber the next round.

Chapters

  1. 00:00Introducing the Buffer Tube Question
  2. 00:16Defining the Buffer Tube
  3. 00:34Internal Components and Function
  4. 01:07Importance and Compatibility
  5. 01:20Humorous Conclusion

Frequently Asked Questions

What is the primary function of a buffer tube on an AR-15?

The buffer tube on an AR-15 or AR-pattern rifle is a crucial part of the operating system. It houses the buffer and recoil spring, which absorb energy when the bolt carrier group (BCG) moves rearward after firing and then propel the BCG forward to chamber a new round.

Where is the buffer tube located on an AR-15?

The buffer tube, also referred to as the receiver extension, is attached directly to the rear of the AR-15's lower receiver. It extends backward from the lower receiver and typically houses the buffer and recoil spring assembly.

What components are found inside an AR-15 buffer tube?

Inside the buffer tube of an AR-15, you will find a buffer (a weighted component) and a recoil spring. These two parts work in conjunction with the bolt carrier group (BCG) to manage the energy of the firing cycle and ensure reliable operation.

Is a buffer tube essential for all semi-automatic rifles?

No, not all operating systems require a buffer tube. However, it is a critical and defining component for AR-pattern rifles and similar direct impingement or gas-operated systems, playing a vital role in their cycling mechanism.

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