Sig Sauer M400 SDI 5.56 NATO 16″ FDE | 30rd

The Sig Sauer M400 SDI is a purpose-built AR-style rifle chambered for 5.56 NATO with a 16-inch cold hammer-forged barrel and a mid-length direct impingement gas system. It ships with a 30-round polymer magazine, full ambidextrous controls, a free-floating M-LOK handguard and a SIG 2-stage Matchlite Duo trigger for a predictable, consistent pull. The rifle is finished in Cerakote and fitted with a 6-position Magpul MOE-SL stock for adjustable ergonomics. For an optic under $1000 that pairs well with this platform, consider the Vortex Viper PST Gen II 1-6×24 for versatile close-to-medium-range performance.

Product Specifications

• The caliber is 5.56 NATO.
• The barrel measures 16 inches and is cold hammer-forged steel.
• The barrel twist rate is 1:7.
• The action type is Semi-Auto.
• The operating system is mid-length direct impingement.
• The muzzle device is a SIG Flash Hider-Compensator.
• The handguard is a free-floating aluminum M-LOK design.
• The stock is a 6-position Magpul MOE-SL unit.
• The trigger is a SIG 2-Stage Matchlite Duo with a flat profile.
• The rifle includes ambidextrous controls for safety, charging handle, bolt catch and mag release.
• The magazine capacity is 30 rounds and it ships with one 30‑round polymer magazine.
• The receiver and external finish is listed as FDE Cerakote.
• The overall length is 36.5 inches.
• The muzzle threads are 1/2×28.
• The UPC is 798681714469.

This M400 SDI is a straightforward, feature-rich modern sporting rifle intended for shooters who prioritize ergonomic controls, a good trigger feel, and modular accessory mounting via M-LOK. The combination of a cold hammer-forged barrel, mid-length gas system and ambidextrous controls makes it suitable for use in precision-oriented practice and competition-style training. Its FDE Cerakote finish and Magpul furniture provide a durable, serviceable platform ready for customization.

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