AR Receiver Extension Extrusion - Courtesy of Centurion Arms.

This guide details the technical modifications involved in the Colt MARS PDW project, a miniaturized M4 variant chambered in a unique 5.56x30mm cartridge. It highlights the extensive part alterations, including receivers and internal components, and explains the rationale behind Colt's decision to shelve the project. The revival by Centurion Arms is also noted. Instruction is provided by Chris Bartocci, a recognized expert on the AR-15/M16 platform.

This guide details the installation of an AR-15 buffer tube using the LAW Tactical Alignment Tool (LAT) in conjunction with a Geissele Reaction Block. Expert instruction from the School of the American Rifle demonstrates how to achieve perfect alignment of the receiver extension with the lower receiver, crucial for proper function and preventing common assembly errors. The process involves securing the components, torquing the castle nut to 38-42 foot-pounds, and ensuring a reliable build.

This video demonstrates the use of the Brownells AR-15 Buffer Tube Lower Receiver Fixture for simplifying buffer tube installation. The fixture securely holds the lower receiver via the grip screw and provides an adjustable, self-aligning support for the buffer tube, ensuring vertical alignment during tightening. This tool also offers additional benefits for staking the castle nut and can be used for other receiver tasks like installing pins and the grip.

This video details a gunsmithing fix for Ruger AR-556 rifles experiencing bolt carrier key clearance issues. The instructor demonstrates how to modify the receiver extension (buffer tube) by filing a notch and smoothing the face to allow the buffer retainer to function correctly while gaining an extra rotation. This modification increases the critical gap between the bolt carrier key and the lower receiver, preventing potential damage.

This guide details the process of installing and removing the CMMG RipStock on an AR-15 platform. It emphasizes using an 8-inch hex wrench to remove a specific screw on the butt plate, which allows the stock to be slid off or on the receiver extension. The video also touches on the P3 screw's function for setting stock positions.

This guide details the process of replacing the buffer and spring assembly in an AR-15 platform rifle. It covers disassembly, removal of the old components, installation of new parts like the Kynshot RB5000 hydraulic buffer or the Geissele Super 42 system, and reassembly with a function check. The video emphasizes proper technique and the benefits of upgraded components for recoil management and reliability.

This guide details the process of diagnosing and repairing an owner-induced feeding problem in an AR-15 upper receiver, specifically addressing a burr on the barrel extension's feed ramp. Expert gunsmith Chad Albrecht demonstrates meticulous inspection, burr removal, and polishing techniques to restore reliable feeding. The video emphasizes that such modifications, while often overlooked, are valid solutions for specific AR-15 malfunctions.

This guide details a diagnostic technique for AR-15 bolt carrier groups, focusing on efficiency rather than simple pass/fail. Developed by Chad Albrecht of School of the American Rifle, it uses custom gauges and cutaway components to illustrate gas dynamics, critical seals, and potential failure points like gas leaks. This advanced method helps troubleshoot functionality issues and understand the nuances of the AR-15's internal gas system.

This video provides a critical, expert-level inspection of a problematic AR-15 Bolt Carrier Group (BCG) by Chad Albrecht of School of the American Rifle. The analysis details numerous manufacturing defects, including an undersized bolt tail, excessive firing pin protrusion, oversized firing pin and cam pin holes, and a failing headspace check. The content highlights the importance of precision gauging in identifying critical failure points that impact rifle reliability and safety.

This guide details a specialized technique for swapping an AR-15 rear takedown pin without requiring a full disassembly. It leverages insights from Chad Albrecht of School of the American Rifle, emphasizing the use of a modified 1/16 inch Allen wrench or a specialized tool to manage the detent. This method is particularly useful for AR-15 variants with collapsible stocks, offering a more efficient approach to maintenance.