The SIG Sauer M400 SDI X-Series is a performance-oriented semi-automatic rifle chambered for 5.56 NATO and .223 Remington. Its 16-inch chrome moly barrel pairs with a low-profile gas block and mid-length gas system for balanced handling and dependable cycling. A free-floating M-LOK handguard supports accessory placement without contacting the barrel, while the SIG Flatblade Match Trigger provides a refined trigger pull. The rifle also features an ambidextrous bolt catch and release, an ambidextrous manual safety, a Magpul SL stock, and a hybrid compensator and flash hider.

Key features

• 16-inch chrome moly barrel chambered for 5.56 NATO and .223 Remington
• Free-floating M-LOK handguard provides flexible accessory mounting
• Mid-length gas system supports smooth, balanced operation
• SIG Flatblade Match Trigger offers a crisp, refined trigger pull
• Ambidextrous bolt catch and release improve controls for left- and right-handed users
• Magpul SL stock provides adjustable length of pull for comfortable handling

The SIG Sauer M400 SDI X-Series combines practical controls, a free-floating M-LOK setup, and a match-style trigger in a ready-to-configure rifle platform.