Sig Sauer M400 Forge

Cold Hammer Forged Barrel

Cold hammer forging compresses the barrel steel around a mandrel rather than cutting rifling away, producing a denser, more fatigue-resistant barrel that holds its accuracy longer under sustained use — the same process used in Sig’s military-contract barrels.

Factory-Mounted ROMEO-MSR Gen II

Every M400 Forge ships with a ROMEO-MSR Gen II 2 MOA red dot already mounted, so there’s no separate optic purchase or zeroing session before the rifle is ready to run. The 2 MOA dot suits fast target acquisition out to typical carbine distances.

TriggerTech Duty Trigger

The two-stage flat blade trigger breaks at a consistent 3.5lb, giving a distinct take-up wall before the break — a trigger feel most shooters find easier to shoot accurately than a single-stage mil-spec trigger, without the cost of an aftermarket upgrade.

16" Barrel, 5.56 NATO

A 16" barrel keeps the M400 Forge in standard rifle-length configuration (no NFA paperwork required) while staying short enough to handle well in a duty or home-defense role. It's chambered in 5.56 NATO and also runs .223 Remington.

Moss Green vs. Black

Both colorways are the same rifle internally. Moss Green Cerakote pairs with a more tactical, outdoors-oriented build; Black is the more common all-purpose finish.

Magazine Capacity Options

The M400 Forge ships with either one 30-round magazine or, in states with capacity restrictions, one 10-round magazine — both use standard AR-15 pattern magazines, so aftermarket mags are widely available.

Frequently Asked Questions

Does the M400 Forge come with iron sights?
No — it ships with the ROMEO-MSR Gen II red dot mounted in place of iron sights.

What caliber is the M400 Forge?
5.56 NATO, which also safely fires .223 Remington.

Is the trigger upgradeable?
The M400 Forge already ships with a TriggerTech two-stage duty trigger, so most shooters won't need an aftermarket upgrade.

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