The M4A1 FSP Rail Interface System II (RIS II) is a two-piece, free-float Picatinny quad rail developed for USSOCOM’s SOPMOD II program. It attaches to the upper receiver with Daniel Defense’s 6-bolt Bolt-Up System and steel barrel nut.
Key features
- Machined from aircraft-grade 6061-T6 aluminum
- Free-float design with patented 6-bolt Bolt-Up System
- Two-piece design for use with a front sight base (FSP) barrel; lower section removes for M203 attachment
- Uninterrupted upper rail with Mil-Spec 1913 Picatinny rails
- Grade 8 mil-spec fasteners
- Mil-Spec Type III hard coat anodized, Black
Specifications
- Manufacturer part number: 0100408030006
- Length: 12.25″
- Weight: 17.1 oz
- Width: 2.23″
- Height: 2.25″
- Inside Diameter: 1.15″
- Material: 6061-T6 aluminum
- Finish: Mil-Spec Type III hard coat anodized
- Mounting: MIL-STD-1913 Picatinny (quad rail)
- Barrel Nut: Steel, Bolt-Up System
- Gas System: Carbine
- Free Float: Yes
Compatibility
Fits mil-spec AR-15 upper receivers with carbine-length gas systems. The FSP version is built to work with a barrel that has a fixed front sight base.
Genuine Daniel Defense product, manufacturer part number 0100408030006. New in the manufacturer’s packaging with full factory warranty. Usually ships within 1-2 business days.
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