The Sig Sauer SIGM400 SDI X is a modern 5.56 NATO rifle built for shooters who want practical performance without compromise. This is a purpose-built platform for hunting, sport shooting, or defensive use—one that doesn't ask you to choose between precision, ergonomics, and reliability. The 16-inch cold hammer-forged steel barrel threaded for accessories gives you a compact, handy rifle that stays fast and maneuverable in the field or at the range, while the moss green Cerakote finish delivers both durability and a rugged aesthetic.
What sets the SIGM400 SDI X apart is its attention to the details that matter in real use. The low-profile gas block feeds a mid-length direct impingement system tuned for balanced performance and controllability. Fully ambidextrous controls mean lefties and righties operate the rifle equally well, and the SIG 2-Stage Matchlite Duo trigger offers the kind of break you'd expect from a precision platform—crisp enough for accurate shooting without feeling hair-trigger fragile. The MLOK handguard gives you modern attachment points for lights, lasers, or supports, and the Magpul MOE-SL stock in a 6-position config lets you dial in your length of pull.
You get one 30-round magazine in the box, so you're ready to load and shoot. The SIG flash hider-compensator helps manage recoil impulse and keeps muzzle flash in check—useful whether you're training, hunting, or working in low light. At 7 pounds with magazine and measuring 36.5 inches overall, the SIGM400 SDI X balances shootability with portability. This is a rifle that does its job reliably, runs smoothly, and doesn't get in its own way.
Whether you're new to the platform or a seasoned 5.56 shooter, the SIGM400 SDI X delivers straightforward, honest performance in a package that won't nickel-and-dime you with unnecessary features or compromise on what matters—accuracy, ergonomics, and durability.
| Caliber | 5.56 NATO |
| Barrel Length | 16 inches |
| Barrel Material | Cold hammer-forged steel |
| Barrel Twist | 1:7 inches |
| Magazine Capacity | 30 rounds |
| Trigger | SIG 2-Stage Matchlite Duo |
| Handguard | MLOK |
| Stock | Magpul MOE-SL, 6-position |
| Overall Length | 36.5 inches |
| Overall Height | 7.1 inches |
| Overall Width | 2.75 inches |
| Weight (with magazine) | 7.0 pounds |
| Frame Material | Alloy |
| Finish | Moss green Cerakote |
The SIGM400 SDI X is a versatile 5.56 NATO rifle suited for sport shooting, hunting, and general purpose use. The balanced 16-inch barrel, quality trigger, and ergonomic controls make it equally at home on the range or in the field.
Yes. The rifle features fully ambidextrous controls, making it comfortable and efficient for both left- and right-handed shooters.
The SIGM400 SDI X ships with one 30-round magazine and a SIG flash hider-compensator already installed on the threaded barrel.
Yes. The MLOK handguard provides modern attachment points for lights, lasers, and other accessories. The upper receiver is configured to accept standard optic mounts.
Sig Sauer
Sig Sauer
Sig Sauer
ATI Ammunition
