Ryan's General Purpose Rifle | AR-15 Build Breakdown

Concept of the General Purpose AR-15 Build

Ryan introduces his personal 13.9-inch AR-15 build, developed over several years in the firearms industry. The rifle is intended as a general purpose rifle, similar in role to a military M4 carbine but updated with modern components. He explains that the configuration has evolved through trial, error, and feedback from more experienced shooters. Every part on the rifle was selected in response to past issues and to support future reliability and versatility. The build is completely custom, assembled from stripped parts rather than a complete rifle, and represents the current culmination of his experience with AR-15 platforms.

Stock, Sling Setup, and A5 Buffer System

At the rear of the rifle, Ryan uses a BCM Mod 2 SOPMOD-style stock. It is a tension-adjusted design without the protruding locking tab found on some Magpul or B5 stocks, giving a flatter profile and a broad cheek weld. The stock includes a rear attachment point where he now mounts his sling. He previously attached an Edgar Sherman Design sling at the end plate, but during an incident the sling caught the charging handle and prevented the bolt carrier group from going fully into battery, forcing a transition to his sidearm. That experience led him to move the sling to the stock and add a V7 lightweight titanium sling swivel. The recoil system is an A5-length buffer setup with a 10-position Sons of Liberty Gun Works buffer tube and a Geissele Super 42 rifle-length spring paired with an A5 buffer. He notes the A5 system’s softer recoil impulse, reduced bolt bounce, and improved shooting characteristics compared to a standard carbine system, and suggests Springco springs as a solid alternative for reducing the characteristic AR-15 “twang.”

Ambidextrous ADM Lower and Geissele SSA X Trigger

The lower receiver is an ADM M4 billet ambidextrous lower, one of the earlier fully ambi designs he encountered. It allows locking and releasing the bolt from both sides of the rifle and includes an ambidextrous magazine release. Although he primarily shoots right-handed and rarely uses the ambi mag release, he appreciates the enlarged bolt controls and overall robustness of the lower. The trigger is a Geissele SSA X with a lightning bow shoe. Ryan favors this two-stage design for its small amount of initial takeup, a defined wall, and a clean break, followed by a short, positive reset. He prefers two-stage triggers over very short, single-stage designs for both safety and precision-focused shooting, aligning with the rifle’s general purpose role. For the grip, he uses a Magpul K2 Plus, citing its more vertical angle and rubber overmold. Despite some minor wear on the rubber over time, he finds it comfortable and installs the same grip on most of his AR-pattern firearms.

Upper Receiver Durability and Out-of-Battery Incident

The upper receiver is a Vltor MUR, chosen for its reinforced construction compared to a standard mil-spec upper. Ryan highlights that the MUR is designed to better contain issues such as out-of-battery events or ammunition problems by resisting splitting or deformation. He recounts experiencing an out-of-battery explosion early in the life of this rifle, which he attributes to a possible headspace issue between the bolt and the Criterion 13.9-inch barrel or a potential overcharged round. Despite the incident, the Vltor MUR upper remained intact and has continued in service on the rifle. He notes that some military units use this upper, and while it is slightly heavier and more expensive than a basic option, he values the added durability and peace of mind it provides.

Psionics NP3 BCG Performance and Reliability

Inside the upper, Ryan runs a Psionics NP3-coated bolt carrier group, which he considers the heart of the rifle. The NP3 coating provides lubricity that keeps the action cycling smoothly, even when the BCG is visibly dirty. He remarks that he has never needed to use the forward assist with this carrier, as it consistently returns to battery without issue. Early on, he encountered a problem within the first few magazines, likely related to headspacing between the original bolt head and the Criterion barrel, which resulted in an out-of-battery event while using Lake City ammunition. Psionics replaced the bolt head, and the carrier has functioned reliably since. Ryan emphasizes that this BCG is a well-machined tool built for hard use, and its performance has reinforced his confidence in the rifle’s reliability.

Criterion 13.9 Barrel Choice and Role in the Build

Ryan identifies the Criterion 13.9-inch barrel as the other core component of the rifle alongside the Psionics BCG. He chose Criterion for its engineering and accuracy, particularly the barrel profile. Instead of a traditional government, heavy, or pencil profile, the Criterion uses a tapered design that begins as a heavier contour near the chamber and progressively thins toward the muzzle. This approach aims to balance rigidity and weight, supporting accuracy while keeping the rifle manageable. He views the barrel and BCG together as the functional center of the rifle, shaping its performance and reliability in the general purpose role he intended for this 13.9-inch AR-15 build.