Sig Sauer M400 Stabilized Direct Impingement 5.56 NATO 16 inch 30 round Flat Dark Earth

The SIG RM400SDI16BFDE M400 SDI is a Sig Sauer AR-15 platform rifle built around a 16-inch chrome-moly barrel with a 1:7 twist and mid-length direct impingement gas system, giving shooters reliable 5.56 NATO performance for duty, competition, and field work; the SDI series focuses on stabilized gas dynamics to improve cyclic reliability and reduce felt recoil, and this model comes optics-ready with an M-LOK Moss Green Cerakote forend and FDE Cerakote receivers to blend into woodland or transitional environments. The SIG two-stage Matchlite Duo trigger with a flat shoe offers predictable break for controlled follow-up shots, while the reduced-angle grip and Magpul MOE-SL six-position stock provide ergonomic control and shooter-adjustable length of pull; ambidextrous safety and forward assist support left- and right-handed handling under stress. Threaded 1/2-28 with a SIG flash hider-compensator allows muzzle device options for flash suppression and recoil management, and the M-LOK/Picatinny rail layout accepts lights, lasers, and backup sights on an optics-ready upper. This rifle requires FFL transfer and serves as a capable service rifle, competition platform, or precision AR for varmint and tactical applications.