Sons of Liberty Gun Works M4-L89 URG 14.5″ 5.56 NATO Upper Receiver Group – Pinned & Welded, Plain Barrel

The Sons of Liberty Gun Works (SOLGW) M4-L89 Upper Receiver Group delivers mil-spec reliability and battle-proven performance in a 14.5″ 5.56 NATO configuration. Designed for serious shooters who demand precision and durability, this URG features a forged upper receiver, SOLGW’s signature L89 7-sided M-LOK rail system, and a Liberty Fighting Barrel — all engineered to withstand the rigors of competition, home defense, and duty use. The pinned and welded muzzle device brings the overall barrel length to the legal 16″ threshold, making this a fully compliant, rifle-configuration upper ready to drop onto any mil-spec lower receiver.

Key Features:
• Caliber: 5.56 NATO
• Barrel Length: 14.5″ (Pinned & Welded to 16″ legal length)
• Rail: L89 7-Sided M-LOK Handguard
• Receiver: Forged Upper
• Barrel: Sons of Liberty Liberty Fighting Barrel
• Configuration: Plain Barrel (no additional muzzle device)
• Mil-spec compatible — fits most standard AR-15 lower receivers

Sons of Liberty Gun Works has built a reputation for uncompromising quality, with small parts and components designed to fit most mil-spec platforms. Whether you’re completing a custom build, upgrading an existing rifle, or stepping into a competition-ready setup, the M4-L89 URG is a top-tier choice that punches well above its price point.

Order online at Deep Roots Rifle Co for fast shipping nationwide, or stop by our gun store in Eustis, Florida to speak with our knowledgeable staff. We’re here to help you find the right parts for your build.