Description
The Sig M400 Tread Coil is a purpose-built, no-frills AR-15 platform rifle chambered in 5.56 NATO/.223 Remington. It features a reliable direct impingement system, a durable 16-inch stainless steel barrel, and comes equipped with a Magpul SL-K telescoping stock for a solid, adjustable fit. This rifle is designed for serious training, home defense, and as a dependable workhorse right out of the box.
Key Features
- 16-inch Stainless Steel Barrel: Provides excellent accuracy and corrosion resistance for consistent performance.
- Magpul SL-K Stock: A compact, lightweight telescoping stock offering a secure cheek weld and quick length-of-pull adjustment.
- Sig Tread M-LOK Handguard: A full-length, lightweight M-LOK handguard for secure accessory mounting without adding bulk.
- Enhanced Tread Trigger: A single-stage, flat-faced trigger designed for a crisp, clean break to improve shot control.
- Ambidextrous Controls: Includes an ambidextrous safety selector for faster, more intuitive operation from either shoulder.
Specifications & Details
| Caliber | 5.56 NATO / .223 Remington |
|---|---|
| Barrel | 16″, Stainless Steel, 1:8 Twist |
| Overall Length | 32.25″ – 35.5″ (Stock Collapsed/Extended) |
| Weight | 6.4 lbs (Unloaded) |
| Magazine Capacity | 30 Rounds (Magazine Included) |
| Stock | Magpul SL-K Telescoping |
Weighing in at a manageable 6.4 pounds unloaded, the Tread Coil balances well for off-hand shooting and extended range sessions. The 1:8 twist rate of its stainless steel barrel stabilizes a wide range of bullet weights, from light 55-grain training ammo to heavier 77-grain defensive loads. This versatility is a key asset when your ammo supply varies. The rifle’s core is built on a mil-spec compatible lower receiver, ensuring broad parts interchangeability with the vast AR-15 aftermarket. That said, the included components are thoughtfully chosen, so you can start training immediately without immediate upgrades. An FFL transfer is required for firearm purchases, a standard and secure process we handle routinely.
Who It’s For
This rifle is for the shooter who values proven performance over flashy gimmicks. It’s an ideal first AR-15 for a Missouri resident seeking a dependable home defense tool, or a perfect second rifle dedicated to training and classes. When it comes to home defense, its 16-inch barrel provides optimal ballistic performance for the 5.56 round in a maneuverable package. It’s also a solid choice for competitive shooters in practical rifle matches who need a reliable, accurate platform that won’t let them down on the clock. The price point of $1127.99 positions it as a serious value in a market cluttered with overpriced or under-built options.
Pros & Cons
Pros: Excellent out-of-the-box trigger, premium stainless steel barrel for the price, lightweight and ergonomic handguard, backed by Sig Sauer’s reputation for quality. The Magpul SL-K stock is a proven upgrade over basic mil-spec options, offering better control. The entire system is drop-in ready for a vast array of standard AR-15 accessories and optics from brands like Vortex, Holosun, and Streamlight.
Cons: Lacks iron sights, so budgeting for an optic is a must. The handguard can get warm during rapid fire—a common trait for slim M-LOK designs easily mitigated with a rail cover. Some may prefer a different stock, but the SL-K is a highly functional starting point.
Frequently Asked Questions
Q: Does this rifle come with any magazines or sights?
A: It ships with one 30-round Magpul PMAG. It does not include iron sights, so you will need to purchase a red dot, LPVO, or iron sight set separately to make the rifle range-ready.
Q: Is the barrel threaded for a muzzle device?
A: Yes, the 16-inch stainless steel barrel features a standard 1/2×28 thread pitch, allowing you to attach a flash hider, compensator, or suppressor mount. A Sig Sauer muzzle brake is installed from the factory.
Q: Can I use .223 Remington and 5.56 NATO ammunition interchangeably?
A: Yes. The chamber is stamped 5.56 NATO, which means it is safe to fire both .223 Remington and higher-pressure 5.56 NATO rounds. This rifle is available at firearms-missouri.com for Missouri residents and nationwide.
Ready to add this capable, straightforward AR-15 to your collection? Contact us to discuss the simple purchase process.
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