The Sig Sauer M400 SDI X is a semi-automatic AR-style pistol chambered in .223 Rem/5.56 NATO with an 11.5-inch cold hammer-forged barrel. It is configured for range, training, and duty-style applications where compact handling and modularity are priorities. The design emphasizes ambidextrous controls, a free-floating M-LOK handguard, and a Magpul BSL folding/telescoping brace for adaptable handling and ergonomic control.
Key Specifications
- The caliber is .223 Rem / 5.56 NATO, suitable for standard 5.56-compatible ammunition and training use.
- The barrel length is 11.5 inches and is described as a cold hammer-forged chrome moly steel barrel.
- The barrel material is chrome moly steel with a black FNC finish noted for durability.
- The twist rate is 1:7, specified for stabilizing heavier 5.56 projectiles.
- The action is semi-automatic in an AR-style pistol configuration.
- The firearm ships with and includes one 30-round removable magazine.
- The handguard is a free-floating M-LOK design for accessory mounting and improved rigidity.
- The brace is a Magpul BSL folding/telescoping pistol brace to support compact carry and storage options.
- The weight with magazine is listed as 5.8 lb, providing a compact balance for handling and training.
This configuration focuses on modular control and reliability, with ambidextrous controls and a two-stage flat blade match trigger for repeatable operation. The free-floating M-LOK handguard and robust barrel materials support accessory mounting and consistent handling in range and duty contexts. The included 30-round magazine and Magpul BSL brace make it a compact option for shooters who prioritize a balance between capacity and maneuverability.
State and shipping notes: the pistol includes a 30-round magazine; be aware that certain states limit magazine capacity to 10 rounds (Hawaii, California, Connecticut, District of Columbia, Illinois, Maryland, Massachusetts, New Jersey, New York, Rhode Island, Vermont, Washington, and Colorado). Additionally, this item is marked with “no direct ship” restrictions for California, Rhode Island, and Washington per supplier attributes.
