Sig Sauer M400 SDI X-Series, 5.56x45mm, 16 inch, 30+1, Anodized Aluminum Receiver

The SIG SAUER M400 SDI X-Series is a ready-to-run, semi-auto rifle that blends competition-grade features with duty and range versatility, and it ships as an FFL-required firearm; built on a black anodized aluminum receiver with a 16" chrome moly steel barrel and 1:7" twist, this 5.56x45mm platform delivers consistent accuracy and built-in capability for common AR-style applications. The X-Series lower brings fully ambidextrous controls – bolt catch and release, selector switch, charging handle and mag release – so right- and left-handed shooters feel natural during rapid drills, and the precision machined lightning-cut upper and lower with a handguard clamp system reduces flex when mounting optics or accessories along the 15" M-LOK handguard. A flatblade 2-stage Matchlite trigger and 30+1 capacity support tight groups and controlled follow-up shots for competitive matches, tactical training, and utility use, while the hybrid compensator/flash hider helps manage muzzle rise and signature on fast strings. The synthetic Magpul SL-K telescoping stock and black polymer grip keep the 7 lb platform maneuverable for patrol-style work, home defense, or range days, and the optic-ready configuration streamlines adding red dots or magnified sights to match your role.