Sig Sauer M400 SDI X 5.56 NATO

The Sig Sauer M400 SDI X is an AR-style semi-automatic rifle chambered in 5.56 NATO designed for range use, duty applications, and general-purpose shooting. Its configuration emphasizes controllability and modularity with a mid-length gas system and ambidextrous controls for right- and left-handed shooters.

The rifle is built on an alloy receiver platform with a free-floating M-LOK handguard and a 16-inch threaded barrel. Ergonomic features include a Magpul MOE-SL adjustable stock and a flat trigger profile two-stage trigger for consistent pull characteristics.

Key Specifications

• The caliber is 5.56 NATO.
• The barrel length is 16 inches.
• The action type is Semi-Auto.
• The operating system is Mid-Length Direct Impingement.
• The barrel twist rate is 1:7.
• The barrel thread pattern is 1/2 in - 28 tpi.
• The muzzle device is a SIG Flash Hider-Compensator.
• The stock type is Magpul MOE-SL, 6-position.
• The magazine included is (1) 30‑round polymer magazine.
• The weight is 7 lbs.

For shooters seeking a modular AR-style platform with 5.56 NATO performance, the Sig Sauer M400 SDI X provides proven controls and accessories in a factory-configured package. Buy the Sig Sauer M400 SDI X 5.56 NATO online today for a professional-grade modern sporting rifle option.