Sig Sauer M400 SDI XSeries Moss 5.56 16" - AR-15 Rifle

A solid 5.56 AR-15 without the fluff: the Sig Sauer M400 SDI XSeries Moss 5.56 16" focuses on reliable function, practical configuration, and durable construction in a package ready to use straight from the box.

The Sig Sauer M400 SDI XSeries Moss 5.56 16" brings 5.56 capability to a semi-automatic AR-15 rifle, using a mid-length direct impingement operating system designed for dependable function in any condition.

Proven Gas System: Running a mid-length direct impingement system that has proven itself across millions of rounds in the field, this 5.56 platform brings that reliability record to every range session and defensive use case.

Well-Balanced Profile: The 16" barrel and free-float handguard combination keep this rifle handy without sacrificing the sight radius and velocity that make the 5.56 cartridge effective.

AR-15 Ecosystem Access: Standard AR-15 compatibility means accessories, replacement parts, and upgrade components are universally available — this rifle will never be an orphan platform.

Low-Maintenance Reliability: A quality finish and properly spec'd components reduce maintenance requirements without cutting corners on durability — more time shooting, less time cleaning.

• Caliber: 5.56
• Barrel Length: 16"
• Gas System: Mid-Length Direct Impingement
• Handguard: Free-Float
• Muzzle Threading: 1/2x28
• Magazine Capacity: 30-Round
• Weight: 6.5 lb
• Finish: With a durable Moss Green Cerakote
• Origin: Made in the USA

Fully compatible with standard AR-15 lower receivers and STANAG-pattern 5.56 magazines. Works with mil-spec carbine buffer systems, standard lower parts kits, and the broad ecosystem of AR-15 aftermarket accessories.

Machined from 7075 aluminum and coated with With a durable Moss Green Cerakote, the receiver set offers durable protection against wear and environmental exposure while maintaining precise fit between components.

Covers the core use cases — home defense, range work, and recreational shooting — without specializing in any single role, making it a reliable all-purpose AR-15.

SIG SAUER is trusted by the U.S. military and law enforcement agencies worldwide. Their AR-15 lineup delivers the same premium quality and engineering that earned SIG that trust. Made in the USA.