SIG SAUER M400 FORGE 11.5-Inch 5.56 NATO Pistol

Description

The SIG SAUER M400 FORGE Pistol is a compact 5.56 NATO AR-platform package built around an 11.5-inch cold-hammer-forged barrel. This exact configuration—manufacturer part number PM400-556N-11B-FORGE—arrives equipped with a ROMEO-MSR Gen II red-dot sight, a 10-inch free-floating M-LOK handguard, a TriggerTech two-stage duty trigger, a Magpul BSL pistol stabilizing brace, and one 30-round polymer magazine.

Compact M400 FORGE configuration

SIG SAUER designed the M400 FORGE Pistol for buyers who want a complete, compact AR-style setup rather than a bare platform that still needs an optic and core furniture. The black anodized configuration measures 27.8 inches collapsed and 29.8 inches overall, with a listed weight of 6.2 pounds. Its reduced-angle grip and brace help keep the rear of the firearm compact, while the full-length top rail and M-LOK forend provide room for compatible accessories.

The operating system is carbine-length direct impingement. An ambidextrous charging handle and ambidextrous safety support access from either side, while a forward assist is included. The result is a familiar control layout with practical upgrades already installed.

11.5-inch cold-hammer-forged barrel

At the center of the platform is an 11.5-inch cold-hammer-forged steel barrel with a 1:7 twist rate. The barrel is chambered in 5.56 NATO and uses a carbine-length gas system. An A2 birdcage flash hider is fitted at the muzzle. This combination gives the M400 FORGE its compact profile while retaining a conventional AR-pattern operating arrangement.

The barrel sits beneath a 10-inch black anodized alloy handguard. The handguard uses M-LOK attachment slots and is paired with a continuous Picatinny top rail, allowing the included optic and other compatible accessories to be positioned without crowding the support-hand area.

ROMEO-MSR Gen II red dot included

This package includes SIG SAUER’s ROMEO-MSR Gen II with a 2 MOA red dot. SIG lists 12 illumination settings, up to 35,000 hours of runtime, and IPX7 waterproof performance for the optic. Because the sight is included in the factory configuration, buyers receive a matched package without needing to select a separate primary optic before initial setup.

A 2 MOA aiming point is fine enough for deliberate target work while remaining easy to acquire at closer distances. As with any electronic sight, confirm mounting security, battery condition, and zero before relying on the firearm.

TriggerTech two-stage duty trigger

The M400 FORGE uses a TriggerTech 3.5-pound two-stage flat-blade duty trigger. The two-stage design provides a defined initial take-up followed by a consistent break, while the flat trigger face offers a repeatable contact surface. This is a notable factory-installed upgrade compared with a basic mil-spec-style fire-control group.

Key specifications

• Manufacturer: SIG SAUER
• Model: M400 FORGE Pistol
• Manufacturer part number: PM400-556N-11B-FORGE
• UPC: 798681744107
• Caliber: 5.56 NATO
• Action: Semi-automatic
• Operating system: Carbine-length direct impingement
• Barrel: 11.5-inch cold-hammer-forged steel
• Twist rate: 1:7
• Muzzle device: A2 birdcage flash hider
• Forend: 10-inch M-LOK alloy handguard with full-length Picatinny rail
• Optic: ROMEO-MSR Gen II, 2 MOA red dot
• Trigger: TriggerTech 3.5-pound two-stage flat-blade duty trigger
• Brace: Magpul BSL pistol stabilizing brace
• Magazine: One 30-round AR-15 polymer magazine
• Color: Black with black anodized receiver finish
• Length: 27.8 inches collapsed; 29.8 inches overall
• Weight: 6.2 pounds

Important purchasing information

This item is a regulated firearm and must be transferred through a federally licensed dealer where required. Magazine-capacity and firearm-configuration restrictions vary by jurisdiction. Confirm eligibility and local requirements before ordering. Package contents, specifications, and compatibility should be checked against the exact MPN and UPC shown above.