Sig Sauer M400 Forge Rifle

5.56 NATO · 30rd · 16" CHF Barrel · TriggerTech 3.5 lb 2-Stage · ROMEO-MSR Gen II Included · FDE Cerakote The Sig Sauer M400 Forge is a 5.56 NATO semi-automatic rifle built around a 16" cold hammer forged barrel with mid-length direct impingement gas system. TriggerTech 3.5 lb two-stage flat blade duty trigger. ROMEO-MSR Gen II 2 MOA red dot included from factory. Full-length free-floating M-LOK handguard with FDE Cerakote finish and full-length Picatinny top rail. Ambidextrous charging handle. Magpul SL-K 6-position adjustable stock. Reduced angle grip. A2 birdcage flash hider on 1/2"-28 threads. 1:7 twist. One 30-round polymer magazine included. FDE Cerakote finish throughout. 6.8 lbs. 35.5" OAL extended, 32.25" collapsed. Backed by SIG Infinite Guarantee—lifetime, fully transferable warranty. SKU: RM400-556N-16B-FORGE-FDE.

16" Cold Hammer Forged Barrel

16" cold hammer forged steel barrel with 1:7 RH twist and mid-length direct impingement gas system. 1/2"-28 90-degree shouldered threads. The CHF process produces consistent bore dimensions and superior rifling for accuracy and longevity. Mid-length gas reduces recoil impulse compared to carbine-length gas on 16" barrels.

TriggerTech 3.5 lb 2-Stage Trigger

TriggerTech 3.5 lb two-stage flat blade duty trigger provides crisp, predictable break. The two-stage design delivers a defined wall before the break for accurate shooting—performance typically requiring aftermarket upgrade on standard AR-15 platforms.

ROMEO-MSR Gen II Included

ROMEO-MSR Gen II 2 MOA red dot included from factory. The factory-installed optic provides immediate fast target acquisition without separate optic purchase or mounting.

M-LOK FDE Cerakote Handguard

Full-length free-floating M-LOK handguard with FDE Cerakote finish and full-length Picatinny top rail. The free-float design maintains barrel harmonics by eliminating barrel-to-handguard contact. M-LOK interface accommodates lights, lasers, grips, and rail sections.

Ambidextrous Charging Handle

Ambidextrous charging handle accommodates left- and right-handed shooters. The ambi design eliminates need for separate left-hand charging handle.

Magpul SL-K Stock

Magpul SL-K 6-position adjustable stock provides adjustable length-of-pull. The SL-K's slim profile maintains compact collapsed length of 32.25".

A2 Birdcage Flash Hider

A2 birdcage flash hider on 1/2"-28 90-degree shouldered threads reduces muzzle flash. The 90-degree shoulder provides consistent muzzle device timing.

FDE Cerakote Finish

FDE Cerakote finish on receiver and M-LOK handguard provides corrosion resistance with distinctive flat dark earth appearance.

SIG Infinite Guarantee

Backed by SIG Infinite Guarantee—lifetime, fully transferable warranty requiring no receipts or warranty cards. The Sig Sauer M400 Forge delivers factory-ready 5.56 performance—TriggerTech 2-stage trigger with ROMEO-MSR Gen II and FDE Cerakote for out-of-box capable AR-15 capability.

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Specifications:

• Manufacturer: Sig Sauer
• Model: M400 Forge
• SKU: RM400-556N-16B-FORGE-FDE
• Caliber: 5.56 NATO
• Firearm Type: Rifle (AR-15)
• Action: Semi-Automatic
• Operating System: Mid-Length Direct Impingement
• Magazine Capacity: 30 rounds
• Magazine Type: Polymer
• Magazines Included: (1) 30-Round
• Barrel Length: 16 inches
• Barrel Material: Cold Hammer Forged Steel
• Twist Rate: 1:7
• Muzzle Threads: 1/2"-28, 90-Degree Shouldered
• Muzzle Device: A2 Birdcage Flash Hider
• Handguard: M-LOK, Full-Length Free-Float, FDE Cerakote
• Accessory Rail: Full-Length Picatinny
• Trigger: TriggerTech 3.5 lb Two-Stage Flat Blade
• Trigger Shape: Flat
• Safety: Ambidextrous
• Grip: Reduced Angle
• Charging Handle: Ambidextrous
• Stock: Magpul SL-K 6-Position Adjustable
• Optic Included: ROMEO-MSR Gen II (2 MOA Red Dot)
• Receiver Finish: FDE Cerakote
• Color: Flat Dark Earth (FDE)
• Overall Length (Extended): 35.5 inches
• Overall Length (Collapsed): 32.25 inches
• Overall Width: 2.7 inches
• Height: 9.4 inches
• Weight: 6.8 lbs
• Warranty: SIG Infinite Guarantee (Lifetime, Fully Transferable)