Geissele URG-I, "near clone" 11.5" Upper Receiver Group - 2025 Factory Production

The Geissele URG-I "near clone" 11.5-inch upper receiver group in 5.56 NATO — Geissele's 2025 factory production of the commercial variant of the USASOC Close Quarter Battle Receiver (CQBR) Block II upper.

• Geissele Mk16 Super Modular Rail in DDC: the same M-LOK handguard designed for the USASOC URG-I program, with T-markings engraved but not painted
• 11.5-inch barrel, 5.56 NATO: chrome-lined, 1:7 twist, carbine-length gas system
• SureFire muzzle device: buyer's choice of 4-prong flash hider or 3-prong WARCOMP, secured with Rocksett (not pinned/welded on the 11.5-inch configuration)
• Geissele Super Charging Handle and mil-spec BCG included

The URG-I — Upper Receiver Group, Improved — is USASOC's adopted replacement upper for the M4A1 carbine. The program specifies a Geissele Mk16 DDC rail, a Daniel Defense cold-hammer-forged 14.5-inch barrel on the standard-length variant, and a SureFire suppressor interface. The 11.5-inch configuration represents the CQB-length variant, sometimes referred to as the CQBR Block II or the Mk18 successor upper.

This Geissele "near clone" production differs from the contract-issued URG-I in specific components. The program-issued upper uses a Colt-forged upper receiver, a Colt bolt carrier group, a Daniel Defense barrel, and a NAVSEA-approved gas block. Geissele's commercial near-clone substitutes a Geissele mil-spec forged upper receiver, a military-grade phosphated and chrome-lined BCG, and a Geissele or FN barrel — all mil-spec grade, but not the exact contract-issued parts. The Mk16 DDC rail, the SureFire muzzle device interface, and the Geissele Super Charging Handle are consistent between the near-clone and the issued upper.

The Mk18 lineage traces back to 2001, when the US Navy developed a shortened upper for shipboard and close-quarters use. Originally fielded by NSW SEAL teams during the early Global War on Terror, the CQB upper concept spread through SOCOM and eventually to conventional forces. The current evolution — the CQBR Block II — incorporates the Geissele Mk16 free-float rail and modern suppressor interface that replaced the earlier KAC RAS quad rail of the Block I era.

The 11.5-inch barrel length means this upper does not require a pinned and welded muzzle device. The SureFire flash hider is secured with Rocksett and supports attachment of a SureFire SOCOM series suppressor. Either muzzle device option — the 4-prong or the 3-prong WARCOMP — is compatible with the SOCOM suppressor line.

Charlie's Custom Clones worked directly with Geissele to bring the first civilian URG-I to market in 2018. We've been building and selling these since the program went commercial. Grab one while they're in production — Geissele runs these in limited batches.