CORE ELITE OPERATIONS CEO-15 BATTLE SERIES 5.56 NATO COMPLETE UPPER RECEVER FOR AR-15 The Core Elite Operations CEO-15 Battle Series Complete Rifle Upper is engineered for reliability, durability, and consistent performance. Designed for demanding use, this complete upper assembly provides a high-quality solution for builders and shooters seeking a ready-to-install AR-15 upper. The upper receiver is manufactured from 7075-T6 aircraft-grade aluminum and finished in a durable black anodize. A 16” barrel constructed from 4150 Chrome Moly Vanadium steel serves as the foundation of the system. The barrel features a corrosion-resistant QPQ black nitride finish and is paired with a custom-designed muzzle brake machined from hardened 4150 steel and treated with a matching black nitride coating. The barrel assembly utilizes a carbine-length gas system with a low-profile .750” gas block and a 304 stainless steel gas tube, ensuring reliable cycling and balanced performance. Surrounding the barrel is a custom-designed 17” lightweight M-LOK handguard that offers strength without excessive weight. The handguard features enlarged ventilation windows along the top rail to enhance airflow and aid in heat dissipation during sustained firing. Internally, the upper receiver is equipped with a Mil-Spec bolt carrier group constructed from heat-treated 8620 steel. The BCG includes a No. 158 steel bolt, shrouded firing pin, and a chrome-lined interior. The gas key is secured using Grade 8 fasteners and properly staked to Mil-Spec standards for reliability and smooth operation. Completing the assembly is the ambidextrous CEO CARNO charging handle, providing smooth and consistent manipulation of the bolt during loading and unloading. All Core Elite Operations complete upper receivers are backed by a lifetime warranty covering all manufacturing defects. SPECS Manufacturer: Core Elite Operations, Inc. Model: CEO-15 Battle Series Complete Rifle Upper Receiver Receiver: CEO-15 Forged 7075-T6 Aluminum Receiver Finish: Black Anodize MIL-A-8625, Type III, Class II, Nickel Acetate Caliber: 5.56×45mm NATO (Safe for .223 Remington) Handguard: CEO-15 17” M-LOK Free-Float Handguard Barrel Length: 16 in Barrel Material: 4150 Chrome Moly Vanadium (CMV) Barrel Profile: MIL-Spec Government Barrel Finish: Black Nitride / QPQ Twist Rate: 1:7 Gas Block Journal Diameter: 0.750 in Feed Ramps: M4 Muzzle Thread: 1/2×28 TPI Charging Handle: CEO CARNO Ambidextrous Charging Handle See all of our AR15s and AR15 Parts here.