The Bravo Company Manufacturing M4 Upper Receiver Assembly is professional grade weaponry. Precision machined to MIL-SPEC from a 7075-T6 aluminum forging provides this upper with exceptional strength. The inside diameter of the receivers threaded bore has been slightly undersized to provide a tighter fit with the barrel extension, resulting in a more accurate rifle.NOTE: Please use a heat gun or hair dryer to warm up threaded bore of receiver if barrel extension is too tight.Features: Laser engraved T-markings No BCM logo etched on the rear of the rail Marked BCM4 over the gas tube port 7075-T6 aluminum Factory assembled forward assist, and ejection port cover Hardcoat Type III, Class 2 anodized Dry film lube on interior bore per MIL-SPEC Made in the U.S.A.