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There are plenty of 11.5 inch AR pistols out there, but not many were shaped by the people who teach shooting for a living. SIG built the M400 SDI X Pistol with direct input from the instructors at the SIG SAUER Academy, and it shows in the details that matter when you are running drills instead of just standing at a bench. The headline feature is the fully ambidextrous control setup: safety selector, charging handle, magazine catch, and a bolt catch and release built into the SDI lower that works from either side. Lefties finally get a gun that does not fight them, and right-handed folks will appreciate how much smoother support-side transitions become.
The trigger deserves real attention here. SIG's 2-stage Matchlite Duo breaks clean in the 4.5 to 6.5 pound range with a flat blade that gives your finger a consistent index point. That is a genuinely good trigger straight from the factory, the kind most people pay to upgrade to. Up front, the 11.5 inch cold hammer forged chrome moly barrel wears a durable FNC finish, spins a 1:7 twist to stabilize heavier 5.56 loads, and runs a carbine-length gas system with a low-profile gas block for smooth cycling. The 1/2×28 threaded muzzle comes topped with a hybrid compensator and flash hider.
The free-floating M-LOK handguard uses a steel lockup design that cuts deflection way down, so you can hang a light, laser, or hand stop on any side without shifting your point of impact. The flat top is optic ready, letting you pick the red dot or LPVO that suits how you shoot. A Magpul BSL brace and a 30-round magazine complete the package, and the whole thing weighs in around 5.8 pounds at 30.2 inches overall. For home use, training classes, or a truck gun that stays handy in tight spaces, this is one of the more complete short 5.56 platforms SIG has put together.
No, this one ships optic ready with a bare flat top rail and no iron sights. That is by design, since most people running a gun like this mount a red dot or low-power variable anyway. Just plan on adding your preferred optic or a set of backup irons before your first range trip.
The SDI lower features a truly ambidextrous bolt catch and release that is unique to this receiver, on top of ambi safety, mag catch, and charging handle. Every control can be worked from either side of the gun. That is a big deal for left-handed users and for anyone practicing support-side or transitional shooting.
The barrel is threaded 1/2×28, which is the standard pattern for 5.56, so it accepts most common muzzle devices and direct-thread suppressors. The factory hybrid compensator and flash hider can be removed if you want to swap on a suppressor mount. The carbine-length gas system on the 11.5 inch barrel also tends to run well suppressed.
Keep it. The 2-stage Matchlite Duo is a legitimate match-style flat blade trigger with a 4.5 to 6.5 pound pull, which is noticeably better than the standard mil-spec triggers found on most factory ARs. For most people it removes the need for an aftermarket trigger entirely.
| UPC | 798681698967 |
|---|---|
| Manufacturer | |
| Manufacturer Part Number | PM400-SDI-11B-BLK |
| Action | |
| ATF Type | MODERN SPORTING RIFLE |
| Barrel Finish | Black FNC |
| Barrel Length | 11.5'' |
| Caliber/Gauge | .223 REM/5.56 NATO |
| Capacity | 30 |
| Color | Black |
| Length | 30.2'' |
| Magazine Included | 1 x 30-Round |
| Model | |
| Number of Magazines | 1 30 rd. Magazine |
| Package Height | 4.2 |
| Package Width | 11.3 |
| Product Type | AR |
| Safety | Thumb |
| Shipping Weight | 9.55 |
| Sights | Optic Ready |
| State Restriction (CA) | NO DIRECT SHIP TO CALIFORNIA |
| State Restriction (RI) | NO DIRECT SHIP TO RHODE ISLAND |
| State Restriction (WA) | NO DIRECT SHIP TO WASHINGTON |
| Thread Pattern | 1/2"x28 tpi |
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