Sig Sauer M400 Forge | 5.56 NATO | 16 in | RM400-556N-16B-FORGE-10

The Sig Sauer M400 Forge is a factory-configured 5.56 NATO semi-automatic rifle built around a cold hammer forged 16-inch barrel and delivered with a ROMEO-MSR Gen II red-dot sight and a 10-round magazine. The rifle’s aluminum M-LOK handguard and Magpul SL-K adjustable stock provide a modular, ergonomic platform for a variety of range and training activities. For those who prefer a standalone optic, the Vortex StrikeFire II is an effective red-dot option under $1000 that pairs well with the factory sight picture and mounting footprint.

Product Specifications

• The caliber is listed as .223 Rem / 5.56 NATO.
• The action is Semi-Auto.
• The barrel length is 16 inches.
• The included optic is the ROMEO-MSR Gen II red-dot.
• The stock is a Magpul SL-K 6-position adjustable stock.
• The handguard is an aluminum M-LOK system with full-length Picatinny rail sections.
• The barrel material is cold hammer forged steel.
• The twist rate is 1:7.
• The magazine capacity is 10+1 rounds and the package includes one 10-round magazine.
• The trigger is a TriggerTech two-stage flat blade rated at approximately 3.5 pounds.
• The muzzle device is a birdcage-style flash hider.
• The overall length is 32.25 inches collapsed and 35.5 inches extended.
• The finished color and receiver finish are listed as black / anodized.
• The UPC is 798681744121.

Configured from the factory for fast sight acquisition, the M400 Forge is well suited to organized range sessions and formal training drills that benefit from a compact, adjustable AR-style platform with an included red-dot optic. The M-LOK handguard makes it straightforward to mount lights, bipods, or other accessories without excess weight, and the adjustable SL-K stock helps fit the rifle to different shooters and positions.

Out of the box the M400 Forge combines a durable cold hammer forged barrel and a practical accessory package that will satisfy shooters who want a ready-to-run modern sporting rifle with a factory-mounted optic and a conservative magazine configuration.

Owners commonly praise the factory-mounted ROMEO-MSR Gen II for reliable sight acquisition, and many note the rifle’s solid out-of-the-box accuracy and build quality.

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