SIG M400 SDI X 5.56 NATO 16" Flat Dark Earth

SIG M400 SDI X: The Modern Sporting Rifle Done Right

The M400 SDI X represents SIG's commitment to building rifles that work as hard as you do. Whether you're a competitive shooter, a hunter, or simply someone who values reliability and performance, this rifle delivers on all fronts.

Design Philosophy

SIG engineered the M400 SDI X to meet the highest standards of performance and reliability. The rifle features a proven mid-length direct impingement operating system—a time-tested design that balances reliability with shootability. The 16-inch barrel provides excellent velocity while keeping the overall package maneuverable.

Ambidextrous Controls

One of the standout features is the full suite of ambidextrous controls:

• Ambidextrous safety selector
• Ambidextrous charging handle
• Ambidextrous bolt catch
• Ambidextrous magazine release

This means left-handed shooters get the same ergonomic advantage as right-handers—no compromises.

Trigger and Accuracy

The SIG 2-Stage Matchlite Duo trigger provides a clean, predictable break that enhances accuracy without sacrificing reliability. The flat trigger design gives you better control and feedback.

Handguard and Accessories

The free-floating M-LOK handguard in Moss Green Cerakote gives you plenty of real estate for mounting optics, lights, and other accessories. The M-LOK system is proven, modular, and widely supported by aftermarket manufacturers.

Stock and Ergonomics

The 6-position Magpul MOE-SL stock allows you to dial in the perfect length of pull. The reduced-angle grip fits naturally in your hand and reduces fatigue during extended shooting sessions.

Specifications at a Glance

• Caliber: 5.56 NATO
• Barrel: 16 inches, chrome-moly steel, 1:7 twist
• Muzzle Device: SIG Flash Hider-Compensator (1/2-28 threads)
• Action: Semi-automatic
• Sights: Optics ready (no iron sights)
• Weight: 7 pounds
• Overall Length: 36.5 inches (33.25 inches collapsed)
• Finish: Flat Dark Earth receiver with Moss Green Cerakote handguard
• Included: One 30-round AR-15 polymer magazine

Why Choose the M400 SDI X?

This rifle bridges the gap between budget-friendly and premium. You get SIG's engineering and quality without paying for features you don't need. The ambidextrous controls, quality trigger, and proven operating system make this an excellent choice for shooters of all skill levels.