This is the first upper in our line of NBS (No Bullshit) Upper Assemblies. We wanted to build an affordable upper assembly without cutting corners. This means using a nitrided steel gas block from an American Manufacturer as opposed to aluminum, quality American Made handguards and using a proven M16 profile Black Nitride BCG paired with an NBS 16" Mid-Length Parkerized Barrel.This also means taking the time to ensure that the upper will function reliably. We dimple every barrel and check for excessive leaks in the gas system using compressed air. We use Permatex 242 on key components while using mil-spec AEROSHELL 33MS Anti-Seize grease on the barrel nut and muzzle device.Lifetime WarrantyUpper ReceiverNBS Slick Side Billet Upper Receiver- M4 Feedramps- .250 takedown pin holesBarrelNBS 16" 5.56 NATO 1:7 Twist Mid-Length Parkerized- Guaranteed to hold a 1.000" MOA at 100 yards with appropriate ammo and shooting techniques.Bolt & Carrier GroupBlack Nitride or Nickel Boron M16 Bolt Carrier Group .223/5.56- Full Auto Capable- 9310 Alloy Steel MPI and HPT Tested Bolt- Case Hardened 8620 Carrier- 4130 Gas Key- Grade 8 Hardware With Proper Staking- Gas Key Sealed With Permatex No.3- 8740 Hard Chrome Firing PinCharging HandleNBS Enhanced AR-15 Mil-Spec Charging HandleGas SystemMid-Length- APOC Armory Nitrided Steel Gas Block- Stainless Steel Mid-Length Gas TubeHandguardNBS 12" or 15" M-LOK Handguard- American MadeMuzzle DeviceMil-Spec A2 Birdcage - Nitride