The URGI 14.5" Daniel Defense Barrel Kit with clone-correct LPGB and Surefire 4-Prong is a comprehensive package for building a military-standard upper receiver group (URG) that reflects the latest specifications used by the USASOC. This kit includes the Daniel Defense Cold Hammer Forged (CHF) barrel at 14.5" in a mid-length gas configuration, the updated low-profile gas block (LPGB), and the Surefire SOCOM 4-prong flash hider. This combination ensures optimal performance while maintaining clone-correct standards.
Initially, the Mk12 gas block was standard, but issues arose when it interacted with the Geissele SMR Mk16 rail, particularly when dropped. The Mk12’s thicker profile sometimes touched the handguard, compromising the setup’s reliability. To resolve this, a modified version—the LPGB—was developed and adopted by the military. Its slimmer profile eliminates this interference, making it the standard in current URGI builds provided to the US Department of Defense (DOD). The LPGB uses a secure taper pin instead of set screws, ensuring a robust, consistent fit for tactical reliability.
This gas block evolution underscores the military’s attention to operational efficiency and equipment precision. For those looking to build a clone-correct URGI, this kit not only matches the aesthetic, but also the exacting specifications found in military service today. By replicating the components of modern USASOC setups, it allows builders to achieve an authentic and functional URGI.
The evolution of the gas block for the URGI (Upper Receiver Group Improved) is rooted in a quest for improved performance and compatibility with specific military components. Understanding this evolution provides valuable context for the changes that took place from the inception of the URGI to its current configuration.
When the URGI was initially designed, the Mk12 gas block was the standard component used. This choice was logical at the time, as the Mk12 gas block was already a proven design, featuring a robust, low-profile construction that had seen extensive use in military applications, especially with the Mk12 SPR (Special Purpose Rifle). The Mk12 block was designed to be durable and easy to secure using bottom-fit set screws. It was suitable for most applications but not specifically optimized for the newer Geissele SMR Mk16 rail system, which was to become standard in the URGI configuration.
As the URGI system began widespread deployment, a specific issue emerged when using the Mk12 gas block in combination with the Geissele SMR Mk16 rail, the chosen handguard for the URGI setup. The Mk12 gas block's thickness became problematic; when installed on the barrel, it was discovered that if the rifle was dropped or put under certain stress conditions, the gas block could come into contact with the inner surface of the SMR Mk16 rail. This could potentially affect the stability and performance of the gas system, a critical concern for military operators who rely on the utmost reliability of their weapon systems.
To resolve these issues, the US Department of Defense asked Daniel Defense for a solution, and the manufacturer looked at a redesign of the gas block. The objective was to maintain a secure and stable fit while reducing the profile and overall thickness to ensure it would not interfere with the Geissele SMR Mk16 rail under any circumstances. Daniel Defense, however, had a COTS (commercial off the shelf) solution. DD had been providing the 14.5" barrel to the civilian market with a thinner and more low profile gas block, and as the Mk16 was thinner that the DD RIS-II and later DD R-III rails, a very slim gas block was needed, and happened to be available. This is the Low Profile Gas Block (LPGB), essentially a refined and slimmer version of the Mk12 gas block. Daniel Defense production team members worked with representatives of the Navy and NSWC Crane to instruct the armorers in the installation of the LPGB with a specific jig used by DD in their plant in Georgia, and the newly revised set of parts from that point forward included the LPGB as part of the delivered parts for the Upper Receiver Group, Improved (URGI).
The LPGB has since become the standard gas block used in current URGI builds and is the configuration delivered to military units today. It reflects the lessons learned from field use and has been specifically engineered to match the dimensions and requirements of the complete URGI system, including compatibility with modern suppressors and the Geissele SMR Mk16 rail.
For enthusiasts and clone builders, the LPGB is now considered clone-correct, as it accurately represents the setup issued to USASOC and other units using the URGI platform. It replaces the Mk12 gas block in current military specifications, ensuring the build aligns with the exact configuration of operational units.
In summary, the shift from the Mk12 gas block to the LPGB in the URGI program highlights the iterative nature of military equipment development. It demonstrates how real-world field data and operator feedback drive changes that optimize performance, reliability, and compatibility with evolving component systems like the Geissele SMR Mk16 rail.
This product kit offers the exact specifications needed for building an authentic, functional, and modern URGI upper receiver group.
Daniel Defense
Daniel Defense
