Description
The Sig M400 Tread, CO Compliant, .223/5.56, 16″ Barrel, 10rd, Magpul SL-K Stock is a factory-built AR-15 platform rifle designed for states with capacity restrictions. It’s a reliable, ready-to-shoot rifle from Sig Sauer that prioritizes function and value, offering a solid entry point into the AR world without the premium price tag. It ships to Missouri and compliant US states.
Key Features
- CO Compliant Configuration: Comes from the factory with a 10-round magazine to meet specific state regulations.
- Sig Sauer Reliability: Built on the proven M400 platform with Sig’s quality control and attention to detail.
- Magpul SL-K Stock: Features a compact, lightweight collapsible stock for improved handling and a shorter length of pull.
- 16-Inch Barrel: The optimal barrel length for .223/5.56, balancing velocity, maneuverability, and legal compliance.
- Tread Handguard: Sig’s proprietary M-LOK compatible handguard offers a slim profile and plenty of real estate for accessories.
- Value Proposition: At $798.99, it undercuts many competitors while delivering the Sig Sauer name and a no-fuss, drop-in ready package.
Specifications & Details
| Caliber | .223 Remington / 5.56x45mm NATO |
| Barrel Length | 16 inches |
| Overall Length | Approx. 32.25-35.5 inches (stock collapsed/extended) |
| Weight | Approx. 6.7 lbs (unloaded) |
| Magazine Capacity | 10 Rounds (included) |
| Stock | Magpul SL-K Collapsible |
The rifle uses a direct impingement gas system and a carbine-length gas tube, which is standard for this barrel length. The upper and lower receivers are made from 7075-T6 aluminum, and the barrel features a 1:8 twist rate, a versatile middle-ground that stabilizes a wide range of bullet weights from light varmint rounds to heavier 77-grain loads. The rifle comes with Sig’s enhanced mil-spec trigger, which is a step above a basic gritty mil-spec unit. Look, you’re getting a complete, functional rifle that fits out of the box—no gunsmithing required to start shooting. It’s built on the ubiquitous AR-15 pattern, meaning parts and upgrades are everywhere. The handguard uses the popular M-LOK attachment system, so adding a foregrip, light, or sling mount is straightforward.
Who This Rifle Is For
This model is ideal for the budget-conscious shooter in a restricted state who wants a trusted brand name without the custom shop price. It’s perfect for a first AR-15, a reliable home defense tool (where legal), or a straightforward range rifle. It’s also a smart choice for someone who appreciates the AR platform’s modularity but doesn’t want to start from a pile of parts. The 10-round configuration makes it a direct solution for buyers in Colorado and other states with similar laws, but it’s a capable rifle for anyone. Given its weight of just under 7 pounds, it handles easily for most shooters.
Pros & Cons: The Practical Tradeoffs
Pros: The biggest pro is the price-to-brand ratio. Getting a complete Sig Sauer AR for under $800 is a genuine value. The CO-compliant setup saves you the hassle of sourcing legal magazines separately. The Magpul SL-K stock is a practical upgrade over a bare-bones option, and the M-LOK handguard is modern and useful. It’s a rifle that works right away.
Cons: To hit this price, Sig makes some choices. The trigger, while decent, isn’t a match-grade unit. The handguard is proprietary, so swapping it for another brand requires a specific barrel nut tool. Some may find the basic furniture a starting point for upgrades. That said, these are the exact tradeoffs that make the $798.99 price point possible—you get a solid core rifle and can upgrade what matters to you later.
Frequently Asked Questions
Q: Is this rifle only for Colorado residents?
A: No. While configured to comply with Colorado’s magazine capacity law, it is legal to purchase in many other states with similar restrictions or for anyone who simply prefers a 10-round magazine. It is available at firearms-missouri.com for Missouri residents and nationwide where compliant.
Q: Can I use standard AR-15 magazines with it?
A: Yes. The lower receiver is a standard mil-spec AR-15 pattern. The rifle comes with a 10-round magazine for compliance, but it will accept any standard AR-15 .223/5.56 magazine that is legal in your state, including popular 30-round PMAGs from Magpul.
Q: What sights or optics does it come with?
A: The Sig M400 Tread CO Compliant model typically ships without iron sights or an optic. This is common for rifles in this price segment, allowing you to choose and mount your preferred sighting system. The upper receiver has a standard Picatinny rail for easy mounting.
So, is the Sig M400 Tread CO Compliant the right budget AR for you? If you want a dependable, brand-name rifle that’s ready to go without breaking the bank, it’s a compelling option. Its sensible specifications and straightforward design make it a practical foundation for both immediate use and future customization. See the full details on our product page.
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