Bravo Company Upper, Mil-Spec, 1913 Rail for Mounting Optics and Accessories, Flat Top, Black BCM4-UR-M4 4URM4

Forged aluminum flattop receiver includes fully-assembled forward assist and ejection port cover and accepts barrels with M4 barrel extensions. All final dimensions machined to correct mil-spec tolerances to readily accept standard AR-15 parts to help you complete an upper receiver. Laser-etched T-marks on Picatinny rail enable easy removal and re-mounting of optics, sights, and other accessories in the correct position. Interior has dry film lubrication to help reduce wear. Inside Diameter for barrel extension slightly undersized for a tighter fit to the barrel and a more accurate rifle. Please use a hair dryer to warm up threaded bore of receiver if barrel extension is too tight.