NBS 16" 5.56 M4 Carbine 1:8 M-LOK Upper Assembly - Black - 21089
Save 24% MSRP: $345.99$261.95
Only 3 left in stock
A quality upper assembly without cutting corners. This means starting with a top tier mil-spec forged upper receiver, using a nitrided steel gas block as opposed to phosphate or aluminum, quality American Made M-LOK handguards and one of the nicest nitrided A2s you’ll find anywhere. This also means taking the time to ensure that the upper will function reliably. We use Permatex 242 on key components while using mil-spec AEROSHELL 33MS Anti-Seize grease on the properly torqued barrel nut and muzzle device.
Bottom line is this: you hear all the time about guys buying a budget upper and it not lasting or having to send it back because of some hardware defect or other issue caused by a careless assembly process. That is why we use top tier components and assemble each unit to the highest standard of quality. We want your upper to function flawlessly out of the box. In fact, we guarantee it will.
Buy with confidence, this upper is backed by our 30 day satisfaction guarantee. Buy it, run it, abuse it, and if you aren’t satisfied you can send it back for a full refund.
Lifetime Warranty
Guaranteed Sub-MOA performance with match grade ammo and proper shooting technique
Made in the USA
NBS — Our In-House Brand for Builders Who Demand Reliable Performance and Real Value.
Designed for builders who demand reliable performance and real value without unnecessary hype or inflated pricing. NBS stands for "No Bullshit."
Built on Strong Industry Partnerships
Through the strong partnerships AR15Discounts has built with trusted suppliers and vendors, we regularly gain access to premium components often manufactured by or for leading industry names. By purchasing these in volume, we bring them to you under the NBS label, ensuring proven quality reaches your build at a fair price, without the added cost of extensive marketing.
Quality You Can Trust
Every NBS product is specified to the exacting standards we apply to our own rifles. Each component features precision CNC machining, American-made key components where it counts, robust materials, dependable steels, and durable finishes engineered for long-term reliability. These items are either sourced from reputable OEMs or carefully assembled in-house using established name-brand elements, maintaining consistent excellence throughout the lineup.
Complete Solutions for Serious Builders
From stripped and complete uppers to bolt carrier groups, handguards, lower parts kits, and beyond, NBS provides a unified, affordable selection that allows you to complete confident, high-performing builds.
Backed by a Limited Lifetime Warranty
All NBS products come with our Limited Lifetime Warranty for the original owner, covering defects in materials and workmanship. AR15Discounts stands firmly behind these parts because, as shooters ourselves, we use and trust them, delivering honest value and gear you can rely on.
| Weight | 60 oz |
|---|---|
| Dimensions | 28 × 5 × 5 in |
| Barrel Finish | Nitride / Melonite |
| Barrel Profile | M4 |
| Cartridge Compatibility | 5.56 NATO |
| Barrel Length | 16" |
| Gas System Length | Carbine |
| Twist Rate | 1-8 |
| BCG / Charging Handle | Not Included |
| MPN | 21089 |
| UPC | 9999921089 |
Compliance
NFA (National Firearms Act) compliance is crucial for legal ownership and transfer of regulated firearms and accessories like short-barreled rifles, suppressors, and certain types of ammunition, ensuring adherence to federal regulations to avoid legal penalties and ensure responsible firearm ownership.
