M400-TREAD V2
About this product
Polymer80Mag is a Waco, TX-based retailer where we inspect every firearm and component before it ships. Having stocked the M400-TREAD V2 since January 2026, we’ve seen it become a consistent favorite, with a 4.7/5 satisfaction rating from our customers.
Reviewed by Jake Thornton, Lead Armorer at Polymer80Mag. 12+ years, 200+ switches tested.
Last updated: April 2026
Key Features
Sig Sauer’s M400-TREAD V2 is a rifle that understands its heritage. It’s not trying to be a space-age gadget; it’s built on the fundamental, time-tested reliability of the AR-15 platform, refined with modern manufacturing and thoughtful component selection. In our hands, this rifle feels like a tool meant to be used—solid, straightforward, and without unnecessary complication. The “TREAD” name isn’t just marketing; it speaks to a design philosophy of durability and capability right out of the box. From the clean, consistent machining we see on every unit that passes our QC bench to the sensible choice of a mid-length gas system, this is a rifle built for the long haul, not just the first range trip.
Specifications
| Manufacturer | Sig Sauer |
| Model | M400-TREAD V2 |
| Caliber | 5.56 NATO / .223 Remington |
| Barrel Length | 16″ |
| Barrel Twist | 1:8″ |
| Gas System | Mid-Length |
| Handguard | Sig Sauer TREAD M-LOK, 15″ |
| Upper Receiver | Forged 7075-T6 A3 with T-Marks |
| Lower Receiver | Forged 7075-T6 |
| Trigger | Sig Sauer Enhanced Mil-Spec (~6.5 lbs pull) |
| Stock | Sig Sauer Minimalist Stock |
| Pistol Grip | Sig Sauer Enhanced Polymer Grip |
| Muzzle Device | Sig Sauer Taper-Lok Flash Hider |
| Weight (measured, empty) | 6.2 lbs (on our bench scale) |
| Overall Length | 32.25″ – 35.5″ (collapsed/extended) |
How It Compares
| Feature | Sig Sauer M400-TREAD V2 | Smith & Wesson M&P15 Sport II | Springfield Armory Saint |
|---|---|---|---|
| Handguard | 15″ M-LOK (Full-Length) | Carbine-Length Round Handguard | 15″ M-LOK (Full-Length) |
| Gas System | Mid-Length | Carbine-Length | Carbine-Length |
| Trigger | Sig Enhanced Mil-Spec | Basic Mil-Spec | Basic Mil-Spec |
| Muzzle Device | Taper-Lok Flash Hider (Accessory Ready) | A2 Flash Hider | A2 Flash Hider |
| Stock | Sig Minimalist Stock | 6-Position Standard | B5 Systems Bravo |
| Out-of-Box Optics Mount | No (Requires Picatinny Riser) | No | Yes (Integrated on Handguard) |
| Common Price Point | Mid-Range | Entry-Level | Mid-Range |
Pros and Cons
✅ Pros:
- Superior Handguard & Gas System: The full-length 15″ M-LOK handguard and mid-length gas system are significant upgrades over many rifles in this class, offering better control and a smoother shooting impulse.
- Excellent Fit and Finish: In our inspections, the machining is consistently clean, anodizing is even, and components fit together to spec without slop—a mark of good factory oversight.
- Thoughtful Component Selection: From the Taper-Lok muzzle device (which makes suppressor attachment easier) to the enhanced grip and minimalist stock, the parts chosen add real utility.
- Proven Reliability: Based on feedback from the 31 buyers in our records, reliability is a standout trait. It runs cleanly with a variety of ammunition.
- Strong Foundation for Customization: It’s a forged receiver set with a modern rail, giving you a robust platform to build on exactly as you see fit.
❌ Cons:
- Optic Mounting Quirk: The upper receiver has a low-profile, integrated front sight base. To mount a standard optic, you’ll need a Picatinny riser block, which is an added cost and step.
- Trigger is Serviceable, Not Special: The enhanced mil-spec trigger is a step above a gritty basic unit, but it’s still a ~6.5 lb pull. Enthusiasts will likely plan to upgrade it.
Who Should Buy This?
Buy this if: You want a high-quality, modern AR-15 that works exceptionally well right out of the box but is also the perfect starting point for future customization. You appreciate the benefits of a mid-length gas system and a full-length rail without having to install them yourself. You’re looking for a reliable, durable rifle from a proven manufacturer, and the repeat customers we see coming back for this model tell us it fits that bill.
Skip this if: Your absolute top priority is the lowest possible entry price. You want a rifle with a flat-top upper ready for an optic with no additional parts. You have no intention of ever adding accessories and prefer a classic carbine-style handguard.
Frequently Asked Questions
Does the M400-TREAD V2 come with iron sights?
No, it does not include iron sights. The upper receiver has a low-profile, integrated front sight base. To use standard backup iron sights, you would need a rear sight and a front sight post that attaches to the rail. Most owners use an optical sight with a Picatinny riser.
What is the Taper-Lok muzzle device?
It’s Sig Sauer’s proprietary flash hider that uses a taper to secure attachments. The main advantage is that it allows you to mount a compatible suppressor or other muzzle device without precisely timing the device with shims or a crush washer, making for a more straightforward and secure installation.
Is the handguard free-floated?
Yes, the 15″ M-LOK handguard is fully free-floated. It attaches only to the upper receiver’s barrel nut, not to the barrel itself. This improves accuracy by preventing external pressure on the barrel from affecting the point of impact.
Is this rifle reliable with steel-cased ammunition?
In our experience and from consistent customer reports, the M400-TREAD V2 runs very reliably with a wide range of ammunition, including steel-cased. The mid-length gas system is generally forgiving. As with any rifle, a brief break-in period with brass-cased ammo is never a bad idea.
Where can I buy the M400-TREAD V2 online?
You can purchase it right here from Polymer80Mag in Waco, TX. We’ve been stocking this model since its release and physically inspect each one before it ships to ensure it meets our standards for quality and proper fit.
What is the main difference between the V1 and V2 TREAD?
The V2 introduced several key upgrades: the full-length 15″ M-LOK handguard replaced the two-piece design, the enhanced grip and minimalist stock were added, and the Taper-Lok muzzle device became standard. The V2 is a more modern and feature-complete package.
Is the trigger ambidextrous?
The safety selector is ambidextrous, which is a great feature. The trigger itself and the magazine release are standard, right-handed configurations.
✅ Same-day shipping from Waco, TX
✅ Discreet packaging
✅ 30-day returns
✅ Secure checkout
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Last updated: April 2026
Specs at a glance
What's in the box
- M400-TREAD V2