USGI M231 & Colt 601 Tool

This YouTube video focuses on USGI (United States Government Issue) armorer's gauges and tools. The title and description indicate a presentation or overview of specialized equipment used for the maintenance, inspection, and potentially repair of firearms, likely within a military or historical context. Viewers can expect to see various measuring devices and tools essential for ensuring firearms are within proper specifications.

This video showcases an unissued U.S. Military M16/A1/A2 Armorer's Tool Kit from Rock Island Arsenal, dated April 1988. The kit is presented in its original packaging, including the cardboard box, packing material, and internal packing list. Several specific tools and gages are highlighted, such as firing pin hole taper plug gages, barrel erosion gages, a muzzle erosion gage, a chamber reflector tool, a field service headspace gage, and various wrenches and blocks. The description also lists NSNs and references the "School of the American Rifle" website and Instagram page.

The WWSD 2017 project introduces a redesigned fire control group inspired by the HK416, featuring a sealed aluminum housing and a primary/secondary sear mechanism instead of a traditional disconnector. This design enhances debris resistance and allows safety engagement with the hammer down, a significant departure from standard AR-15s. It also incorporates an ambidextrous safety selector with 45 or 90-degree throw options.

This video details the diagnosis and repair of a feeding issue on a Sons of Liberty Gun Works East India upper receiver. The root cause was identified as a sharp burr on the barrel extension's feed ramp, causing rounds to jam. The solution involved polishing the feed ramps and adding a secondary bevel, replicating Colt's design, which successfully resolved the malfunction.

This video demonstrates the internal mechanics of an AR-15 bolt carrier group using cutaway models. It highlights the importance of internal bore dimensions for gas system efficiency and explains how to diagnose potential issues like gas leaks. The demonstration covers the cycle of operation, critical seals, and common manufacturing defects, offering advanced insights for AR-15 maintenance and troubleshooting.

This video provides a detailed autopsy of a faulty AR-15 Bolt Carrier Group (BCG). The analysis reveals critical manufacturing defects including an undersized bolt tail failing gauges, excessive firing pin protrusion causing pierced primers, an oversized firing pin hole, and an oversized cam pin hole leading to headspace issues. These flaws significantly compromise the BCG's function and reliability.

This video demonstrates a specialized technique for swapping an AR-15 rear takedown pin without full firearm disassembly. It highlights the use of a custom-fabricated tool, often made from a 1/16 inch Allen wrench, to depress the detent. The method allows for efficient pin replacement, particularly useful on rifles with staked castle nuts, by leveraging the old pin to guide the new one into place.