How to Assemble an AR-15 Bolt Carrier Group Presented by Larry Potterfield of MidwayUSA

Published on July 19, 2018
Duration: 2:20

This video details the assembly of an AR-15 Bolt Carrier Group (BCG) by Larry Potterfield of MidwayUSA. Key steps include accurately measuring firing pin protrusion using specialized gauges and calipers, ensuring it falls within the .028 to .036 inch range. The process also covers correctly inserting the bolt into the carrier with the extractor oriented, installing the cam pin to allow free movement, and securing the firing pin with its retainer pin.

Quick Summary

The correct firing pin protrusion for an AR-15 bolt carrier group should be between .028 and .036 inches. This measurement is critical for proper ignition and function, ensuring the firing pin strikes the primer with adequate force. Use a protrusion gauge and digital calipers for accurate measurement.

Chapters

  1. 00:00Introduction & Firing Pin Protrusion
  2. 00:11Measuring Firing Pin Protrusion
  3. 01:04Bolt and Carrier Assembly
  4. 01:14Installing the Cam Pin
  5. 01:38Firing Pin and Retainer Installation
  6. 02:00Final Upper Receiver Assembly

Frequently Asked Questions

What is the correct firing pin protrusion for an AR-15 bolt carrier group?

The correct firing pin protrusion for an AR-15 bolt carrier group should be between .028 and .036 inches. This measurement is critical for proper ignition and function, ensuring the firing pin strikes the primer with adequate force.

How do you properly assemble the bolt into the AR-15 carrier?

To assemble the bolt into the AR-15 carrier, insert the bolt ensuring the extractor is positioned towards the right side of the carrier. Then, align the cam pin hole in the bolt with the slot in the carrier before installing the cam pin.

What is the function of the firing pin retainer pin in an AR-15 BCG?

The firing pin retainer pin, inserted from the left side of the carrier, prevents the firing pin from sliding out the rear of the bolt carrier group. It ensures the firing pin remains captured within the assembly.

What tools are needed to measure firing pin protrusion accurately?

Accurate measurement of firing pin protrusion requires a protrusion gauge and precision digital calipers, such as Mitutoyo. The gauge is zeroed on a flat surface, then used with the calipers to measure the difference.

Related News

All News →

More Gunsmithing & DIY Videos You Might Like

More from MidwayUSA

View all →