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Most ARs in this class come with a gritty mil-spec trigger and a bare top rail, and the upgrade list starts before you ever leave the counter. The M400 Forge flips that script. SIG built this one with the parts people usually buy later: a TriggerTech 3.5 lb two-stage flat blade duty trigger, a Breek Arms Warhammer ambidextrous charging handle, and a ROMEO-MSR Gen II red dot already on the rifle. That optic runs a crisp 2 MOA dot with 12 illumination settings and up to 35,000 hours of battery life, so it is genuinely ready for serious use, not just a throw-in.
The barrel is where the Forge really separates itself. It is a 16 inch cold hammer forged tube produced on the same machinery SIG uses for its premium MCX line, with a 1:7 twist that stabilizes everything from light varmint loads to heavy 77 grain match ammo. FMC coating inside and out protects against wear and corrosion, and the mid-length gas system keeps bolt velocity down for smoother cycling, softer recoil, and longer parts life. The muzzle wears a standard A2 flash hider on 1/2×28 threads with a 90 degree shoulder, so brakes and suppressor mounts thread on without any fitment headaches.
Ergonomics are handled by a free-floating M-LOK handguard with a full-length Picatinny top rail, a Magpul SL-K six-position adjustable stock, and ambidextrous safety and magazine release. The Moss Green Cerakote finish gives it a clean, earthy look that stands apart from the sea of black rifles on the rack. One 30-round Magpul PMAG comes in the box, and the whole rifle is covered by the SIG Infinite Guarantee, a fully transferable lifetime warranty with no registration or receipts required.
Whether you want a do-it-all carbine for home defense, range days, or carbine classes, the Forge is a strong pick for anyone who would rather shoot their new rifle than spend the first six months upgrading it.
Yes, it ships with a SIG ROMEO-MSR Gen II red dot mounted from the factory. It runs a 2 MOA dot with 12 illumination settings, IPX7 waterproofing, and up to 35,000 hours of runtime. You will still want to confirm zero with your preferred ammo, but the rifle is genuinely usable the day you bring it home.
The Forge sits a step above the Tread in SIG's lineup and adds the parts most people end up buying anyway. You get a TriggerTech 3.5 lb two-stage duty trigger instead of the Matchlite, a cold hammer forged barrel made on SIG's MCX machinery, a Breek Arms Warhammer charging handle, and the included Romeo MSR Gen II red dot. Add up those upgrades on their own and the Forge starts looking like the better value for most buyers.
A 1:7 twist is on the faster end, which means it stabilizes heavier bullets really well. It handles common 55 grain range ammo just fine, but it really shines with 62 to 77 grain loads, including heavier match and defensive ammunition. That makes it a flexible choice whether you are plinking or running serious training.
Yes. The barrel uses standard 1/2×28 threads with a 90 degree shoulder, so common brakes, comps, and suppressor mounts install without fitment issues. That is a welcome change from SIG's older tapered shoulder design, which caused clearance problems with some aftermarket devices.
The rifle comes with the ROMEO-MSR Gen II red dot already mounted and one 30-round Magpul PMAG. It is also covered by the SIG Infinite Guarantee, a fully transferable lifetime warranty that does not require receipts or registration.
The Moss Green models wear a Cerakote finish over the receivers and handguard, while the base black version is standard hard anodized. Cerakote adds an extra layer of corrosion and wear resistance on top of the looks. It is a durable ceramic-based coating that holds up well to regular range use and field carry.
| UPC | 798681744206 |
|---|---|
| Manufacturer | |
| Manufacturer Part Number | RM400-556N-16B-FORGE-MSGRN |
| Action | |
| Barrel Finish | Black |
| Barrel Length | 16" |
| Caliber/Gauge | .223 REM/5.56 NATO |
| Capacity | 30 |
| Color | GREEN |
| Magazine Included | 1 x 30-Round |
| Model | |
| Number of Magazines | 1 30 rd. |
| Product Type | AR |
| Shipping Weight | 9.7 |
| Sights | Optics Ready |
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