SIG Sauer M400 Forge 5.56 NATO Rifle with ROMEO-MSR Red Dot

The SIG Sauer M400 Forge 5.56 NATO Rifle (brand part no. RM40055616FORGCON) pairs a 16-inch cold hammer-forged barrel with a factory-mounted SIG ROMEO-MSR Gen II 2 MOA red dot, giving shooters an optic-equipped rifle ready to run straight out of the case. SIG Sauer, one of the most trusted names in modern firearms, finishes this Forge-series build in a Concrete Gray Cerakote over an alloy frame for a durable, low-glare look. Built for home defense, range training, and duty-style use, the rifle runs a mid-length gas system for softer recoil and pairs a TriggerTech 3.5-pound two-stage flat-blade duty trigger with a 6-position Magpul SL-K stock for a crisp trigger pull and a comfortable, adjustable length of pull. A 15-inch M-LOK handguard with full Picatinny rail coverage and an ambidextrous charging handle round out a rifle built to accept lights, optics, and grips without added gunsmithing.

Key Specifications

• Chambered in 5.56 NATO, the standard modern sporting rifle cartridge with broad ammunition availability.
• The 16-inch cold hammer-forged barrel with a mid-length gas system balances accuracy, barrel life, and a softer recoil impulse.
• A 1:7 rate of twist stabilizes the full range of 5.56 bullet weights.
• Includes a factory-mounted SIG ROMEO-MSR Gen II 2 MOA red dot, ready to run without buying a separate optic.
• The TriggerTech 3.5-pound two-stage flat-blade duty trigger delivers a crisp, consistent pull for faster, more accurate follow-up shots.
• A 6-position Magpul SL-K stock adjusts length of pull for different shooters and gear setups.
• The 15-inch M-LOK handguard with full Picatinny rail accepts lights, grips, and other accessories at any position.
• An ambidextrous charging handle speeds manipulation for both left- and right-handed shooters.
• Finished in Concrete Gray Cerakote over an alloy frame for a durable, low-glare exterior.
• Ships with a 30-round magazine for extended capacity between reloads.

Frequently Asked Questions

Does the M400 Forge come with an optic? Yes, it ships with a factory-mounted SIG ROMEO-MSR Gen II 2 MOA red dot.

What caliber does it shoot? It is chambered in 5.56 NATO.

Is the stock adjustable? Yes, the 6-position Magpul SL-K stock adjusts to fit different shooters.

Buy the SIG Sauer M400 Forge 5.56 NATO Rifle

Order the SIG Sauer M400 Forge 5.56 NATO Rifle from Schaefer Defense, a Lubbock, Texas gun shop that ships nationwide to your local FFL for fast, insured delivery. SIG Sauer built the Forge series to arrive optic-ready, saving you the cost and hassle of sourcing a red dot separately. Compare it with the rest of our semi-auto rifles to find the duty-ready build that matches your mission.