The Sig Sauer SIGM400 TREAD COIL is a high performance, semi automatic rifle designed for versatility and reliability, chambered in 5.56x45mm NATO with a 16 inch barrel and a 30 round magazine. It is built to deliver precision and control on the range and in the field.
The TREAD line exists to give shooters a genuinely complete modern rifle out of the box rather than a base gun that needs a list of upgrades before it feels finished.
What the Sig Sauer SIGM400 TREAD COIL Brings to the Table
This rifle is aimed at shooters who want one carbine that covers tactical training, defensive use, and recreational range work. The 5.56x45mm NATO chambering keeps ammunition affordable and available, which matters enormously when you actually train.
The COIL variant is defined by its handguard and furniture package. A free floating M-LOK handguard means the barrel is not touching the rail, so pressure from a bipod, sling, or barricade does not shift your point of impact.
New shooters get an easy rifle to learn on. Experienced ones get a platform they can configure endlessly without replacing core components first.
Key Features
The hardware that comes standard:
- 16 inch barrel chambered in 5.56x45mm NATO for versatile, everyday shooting
- 30 round magazine capacity in a semi automatic configuration
- Free floating M-LOK handguard for accessory mounting and consistent accuracy
- Adjustable stock that fits different shooters, body armor, and shooting positions
- Polished trigger for a cleaner break than a standard mil spec unit
- Optics ready with a hard coat anodized finish and no iron sights included
Specifications and Handling
Weight is approximately 7.5 pounds, and overall length runs 35.5 inches collapsed and 38.5 inches extended. That is a genuinely compact package for a 16 inch rifle, and the adjustable stock is what makes both numbers possible.
The polished trigger is one of those upgrades that is hard to appreciate until you shoot back to back with a standard unit. A cleaner break means less disturbance of the sights as the shot goes, which shows up directly on target.
Hard coat anodizing protects the aluminum receivers and handguard against wear and corrosion. It is the same class of finish used on duty rifles because it survives holsters, cases, barricades, and weather.
Since the rifle ships optics ready with no iron sights, plan your sighting system as part of the purchase. A red dot suits close and mid range work, while a low power variable optic extends the rifle out to longer distances.
The adjustable stock is worth setting up properly rather than leaving at whatever position it arrived in. Length of pull changes how you index the rifle, and the Sig Sauer SIGM400 TREAD gives you several positions to find the one that fits your build and your gear.
Free floating the handguard is the single design choice that most affects accuracy on a rifle like this. With no contact between rail and barrel, the barrel vibrates the same way shot after shot regardless of how hard you load the front end.
Setup, Accessories, and Maintenance
M-LOK gives you direct attachment for lights, bipods, hand stops, and sling mounts without adapter rails. Mount your light where your support hand naturally sits, and keep the front of the handguard clear so nothing snags.
Break in is simple. Run a few hundred rounds of quality ammunition, clean normally, and check that all mounting hardware is torqued correctly after the first session, since new screws settle under recoil.
Maintenance follows standard AR practice. Keep the bolt carrier group clean and properly lubricated, watch the gas rings and extractor spring as round counts climb, and inspect the buffer and spring periodically. Browse the rest of our firearms collection for complementary rifles and platforms.
Versatile, well equipped, and backed by a serious manufacturer in SIG Sauer, the Sig Sauer SIGM400 TREAD COIL is a carbine that needs nothing before it earns its keep. Like every firearm, it ships to your local licensed dealer for transfer after your background check.
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