PTG Chamber/Throat Function Gauges

This comprehensive inspection of multiple Smith & Wesson M&P 15 Sport II rifles reveals a range of manufacturing and assembly issues. The video details checks for bolt lock, magazine release function, magazine well dimensions, selector engagement, forward assist operation, muzzle device alignment, receiver extension alignment, rail screw torque, takedown pin bores, gas block screw torque, barrel extension alignment, buffer spring length and compression, gas port alignment, headspace, trigger pull weight, castle nut torque, and carrier key alignment. Several firearms exhibited problems including sticky magazine releases, tight magazine wells, misaligned muzzle devices, clocked receiver extensions, undertorqued rail screws, loose gas block screws, short buffer springs, and loose castle nuts.

This video debunks the common misconception that the bolt must be fully disassembled (extractor and ejectors removed) to check headspace. Instructors Steve and Caleb demonstrate that for most firearms, including bolt actions and AR-style platforms, headspace can be accurately checked with the bolt intact. They explain that the mechanical leverage involved in closing the bolt negates the minimal resistance from the extractor and ejector springs, and that the ejectors should naturally seat flush. While acknowledging potential extractor interference with some gauges, they offer solutions like using cut gauges or removing only the ejector for peace of mind.

This video provides a detailed physical inspection of two 12.5-inch Hodge 5.56 carbine gas barrels. The instructor meticulously gauges gas port sizes, checks headspace, throat dimensions, erosion, straightness, and thread runout. A borescope is used to examine the internal condition of the barrels, including the chamber, rifling, and crown, highlighting the high-quality finish typical of match-grade barrels.

Chad from School of the American Rifle explains the extensive use of gauges in his AR-15 training. He emphasizes that gauging removes guesswork, ensuring proper function and safety by verifying component tolerances and gas system efficiency. This approach blends gunsmithing expertise with armorer knowledge to address the complexities of the civilian AR-15 market, where part variations are significant.

This guide details the process of assembling a precision rifle barrel using a barrel nut system, emphasizing the critical role of proper tools and headspace measurement. It highlights the importance of securing components correctly and using a torque wrench to achieve the manufacturer's specifications. The discussion also touches upon the advantages and considerations of pre-fit shouldered barrels versus barrel nut systems, with expert advice from custom rifle builders and competitive shooters.

Jim Fuller, a seasoned firearms instructor and builder, details the intricacies of building an AK-pattern rifle, emphasizing the need for specialized tools and a deep understanding of the platform's mechanics. He highlights the importance of proper riveting, barrel installation, and headspace checks, contrasting the AK build process with that of an AR-15. Fuller also touches on the durability and longevity of AK firearms and the evolving market for US-made AK components.

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.