Daniel Defense Rail Assembly M4A1 RIS II FSP 12.25″ FDE 01-004-08030

Description

Description

The Daniel Defense M4A1 FSP Free Float Rail Interface System (RIS II) 12.25″ FDE (01-004-08030) is a battle-proven quad rail handguard engineered to meet the rigorous demands of military and professional end users. Originally developed for the USSOCOM SOPMOD II program, this rail system delivers exceptional strength, modularity, and reliability in real-world conditions.

Designed around a free-floating barrel configuration, the RIS II enhances accuracy by eliminating pressure on the barrel while maintaining consistent performance under sustained fire. The system features a two-piece design, allowing the lower rail section to be removed for compatibility with accessories while preserving a rigid upper structure.

Machined from aircraft-grade 6061-T6 aluminum, the 12.25″ rail offers outstanding durability without excessive weight. Its continuous Mil-Spec 1913 Picatinny rail system provides ample space for mounting optics, lights, grips, and other mission-critical accessories. The integrated FSP (Front Sight Post) cutout ensures proper fitment with rifles utilizing a fixed front sight base, making it ideal for classic M4A1-style builds.

At the core of the system is Daniel Defense’s proprietary Bolt-Up mounting system, utilizing military-grade fasteners to create a secure, rock-solid lockup between the rail and upper receiver. This design ensures consistent zero retention and long-term durability even under harsh operational conditions.

Finished in a rugged Flat Dark Earth hard coat anodizing, the RIS II is built to resist wear, corrosion, and abrasion. Trusted by professionals and widely recognized as one of the most durable rail systems available, the Daniel Defense M4A1 FSP RIS II is an excellent choice for shooters seeking a proven, full-length quad rail platform for their AR-15.