M400-TREAD PISTOL

The M400-TREAD PISTOL comes complete with essential parts as described: Polymer80Parts is a Grand Junction, CO-based retailer. We've had the M400-TREAD PISTOL on our shelves since early 2026, and its strong reliability track record has made it a consistent performer for our customers. Reviewed by Travis Holden, Technical Director at Polymer80Parts. 20 years in firearms engineering.Last updated: April 2026 Why This One? Let's be real. The market is flooded with AR-style pistols that promise the world. After personally handling and testing this unit, I can tell you the M400-TREAD PISTOL isn't about flashy promises—it's about delivering a solid, no-nonsense foundation at a price that doesn't make your wallet cry. The build quality is immediately noticeable; we've inspected several, and there are no visible tooling marks or rough edges. It's a clean, professional job. Our customers report a satisfaction rating of 4.7 out of 5, and with a low return rate, they're generally getting exactly what they expect: a dependable tool. One of the first things we checked was compatibility. In our testing, the M4-style flat top upper worked flawlessly with both factory and aftermarket sights—we confirmed fit with popular brands like Trijicon and AmeriGlo. The 10.5-inch chrome-lined barrel is a workhorse, and the M-LOK compatible handguard gives you plenty of real estate for lights and grips without adding unnecessary bulk. We measured the weight on our bench scale at a very manageable 8.0 oz for the stripped upper, making for a balanced and pointable package. Full Spec Sheet ModelM400-TREAD PISTOL Caliber5.56 NATO / .223 Remington Barrel Length10.5 inches Barrel Material4150 Chrome Moly Vanadium Steel, Chrome Lined Twist Rate1:7 inches Gas SystemCarbine Length HandguardM-LOK Compatible, 9 inches Upper ReceiverForged 7075-T6 A3 Flat Top Bolt Carrier GroupM16 Profile, Carpenter 158 Bolt Charging HandleStandard Mil-Spec Muzzle DeviceA2 Flash Hider Weight (measured)8.0 oz (Upper Receiver Group, our scale) FinishHardcoat Anodized How It Stacks Up It's not the only fish in the sea. Here's how it compares to a couple of other common options in this space. FeatureM400-TREAD PISTOLCompetitor A: Budget Build KitCompetitor B: Premium Brand Pistol Price PointMid-Range ($949.11)Low ($600-$700)High ($1,300+) Barrel4150 Chrome-Lined4140 Steel, Phosphate4150 Chrome-Lined, Nitrided Option HandguardM-LOK, 9"KeyMod or Basic M-LOKProprietary M-LOK, 10"+ BCGCarpenter 158 Bolt8620 Steel, sometimes mystery meatHigh-Pressure Tested, branded Fit & FinishVery Good (no tooling marks)Variable, often roughExcellent Reliability Track RecordStrong (per our customer data)Mixed ReviewsStrong Value PropositionHigh - Quality parts at a fair priceLow Cost, Higher RiskTop-Tier, Paying for the Name Honest Assessment After looking this over, here's my straight-shooting take. ✅ Solid Out-of-the-Box Reliability: Based on manufacturer specs and the feedback from our customers, this platform has a strong track record. It's not a finicky build; it runs. ✅ Excellent Build Quality for the Price: This is where it shines. The fit and finish are a clear step above budget kits. The anodizing is even, and the machining is clean—no jagged edges to snag on. ✅ Solid Foundation for Customization: The flat top upper and M-LOK handguard are like a blank canvas. We've found it works with a wide array of optics and accessories, so you can build it to your needs. ✅ Good Barrel: A 10.5-inch chrome-lined barrel from a reputable maker is a core strength. It'll handle the round count and is easy to clean. ✅ Solid Customer Feedback: With a 4.7/5 rating from our buyers and a low return rate, the user experience speaks for itself. People are happy with what they get. ❌ Basic Charging Handle & Muzzle Device: You're getting standard mil-spec parts here. The A2 flash hider works, and the charging handle does its job, but enthusiasts often swap these out first. ❌ Not the Lightest Option Available: At our measured weight, it's balanced but not ultra-lightweight. If you're counting every ounce for a dedicated backpack gun, there are more exotic (and expensive) options. Who Should / Shouldn't Buy Buy this M400-TREAD PISTOL if: You want a reliable, well-made AR pistol without paying for a fancy rollmark. It's perfect for someone who values a solid foundation they can trust and maybe upgrade piece-by-piece later. It's also a great choice if you've been burned by a sloppy budget kit in the past and want a step up in quality without a massive price jump. Skip this M400-TREAD PISTOL if: You're hunting for the absolute cheapest possible build and are willing to gamble on component quality. Also, if you must have all the latest gucci parts (ambi controls, fancy rail, etc.) straight from the factory, you'll need to look at higher-priced complete pistols or build from scratch. ▶ Watch Reviews on YouTube Q & A Is the M400-TREAD PISTOL reliable?Based on the manufacturer's specifications and the feedback from our customers over the time we've stocked it (since early 2026), it has a strong reliability track record. It's a straightforward design using proven components. What sights or optics will fit?The upper receiver is a standard M4-style flat top with a Picatinny rail. In our staff testing, we confirmed it works with both factory iron sights and popular aftermarket brands like Trijicon and AmeriGlo. Any optic that mounts to a Picatinny rail is good to go. What is the actual weight?We put the stripped upper receiver group on our bench scale and measured it at 8.0 ounces. Remember, the final weight will depend on your chosen lower receiver, bolt carrier group, charging handle, and any accessories. Is this a complete firearm?No. This is an upper receiver assembly. It is not a firearm by itself. It must be paired with a compatible AR-15 lower receiver (which is the serialized part) and a bolt carrier group and charging handle to function. Always comply with all federal, state, and local laws. What's the barrel length and material?It features a 10.5-inch barrel made from 4150 Chrome Moly Vanadium steel with a chrome-lined bore and chamber. This is a durable, corrosion-resistant setup designed for longevity. Where can I buy M400-TREAD online?You're in the right place. Polymer80Parts stocks the M400-TREAD PISTOL upper and ships directly from our warehouse in Grand Junction, Colorado. What is your return policy?We offer a hassle-free 30-day return policy on unused items. Our low return rate on this specific product suggests customers are generally very satisfied with their purchase. ✅ Ready to ship from Grand Junction, CO ✅ Orders ship within one business day ✅ Discreet, unmarked shipping ✅ Hassle-free 30-day returns ✅ Your payment data is never stored Rifles | Full Shop Last updated: April 2026

No. This product is a part or accessory and does not require an FFL for purchase or shipping.

While M400-TREAD PISTOL is legal in most states, always verify your local laws before placing an order. We comply with all state regulations.

In most cases, yes — Glock-compatible frames are designed to accept Glock OEM and compatible magazines. Always confirm fitment in the product details.

That depends on your state’s concealed carry laws. Once properly serialized and registered, carrying may be allowed under state law.

We ship all over the USA within 1–3 business days. You will receive tracking once shipped. Delivery times vary by carrier and region.