How to Install a Micro Buffer Tube Kit on a Pre-Assembled Lower Receiver

how to install a micro buffer tube kit on a pre assembled lower receiver
How to Install a Micro Buffer Tube Kit on a Pre-Assembled Lower Receiver 2

Hey guys, this is Mitchell with CBC Industries. Today, we’re going to walk through how to install one of our micro buffer tube kits on an AR pistol with a pre-assembled lower receiver. If you need any help with assembling a lower receiver, make sure to check out the video at the top of this article!

Tools and Materials Needed

  • Micro buffer tube kit
  • Pre-assembled lower receiver
  • Castle nut
  • End plate
  • Pivot pin
  • Detent
  • Vice block
  • Tapco wrench or similar tool
  • Receiver extension

Step-by-Step Installation Guide

1. Prepare the Buffer Tube

To start, take your regular buffer tube and thread your castle nut onto it. Unlike the standard buffer, ensure that the larger notches on the castle nut are facing towards the back end of the buffer tube.

2. Install the End Plate

Next, install your end plate. The notch on the bottom of the end plate should face out or up, depending on how you’re looking at it. The nipple in the middle of the end plate will drop into the notch on the buffer tube.

Thread the Buffer Tube into the Receiver Extension

Begin threading your short buffer tube into the receiver. Once it is partially threaded, you can secure it onto your vice block.

4. Install the Pivot Pin and Detent

Install your pivot pin and detent in the rear of the lower receiver. For a detailed walkthrough, refer to our previous lower assembly video.

Adjust for Short Buffer Tubes

Typically, you would now install your buffer retainer and buffer retainer spring. However, due to the size of the micro buffer tubes, this may not be possible. With this specific kit, installing the buffer retainer and spring would cause the buffer tube to protrude too far, preventing the upper receiver from closing properly. It is also crucial to match the buffer weight to the specific build and caliber to ensure proper functioning and prevent issues like bolt bounce in AR systems.

6. Secure the Castle Nut

Tighten the castle nut by hand, ensuring the end plate is properly seated. While standard Magpul wrenches work for most mil-spec buffer tubes, the smaller size of micro buffer tubes means a Tapco wrench is recommended. The small nipple in the center of the Tang on the Tapco wrench is ideal for grabbing and tightening the teeth on the castle nut.

7. Final Assembly

You will install the end cap, spring, and body for the spring once your upper receiver is assembled and attached to the lower receiver. We will cover this in our next video, so stay tuned.

With the proper configuration, this setup will work fine.

You can find this product and many more like it at our website: Thanks for watching!