Centurion Arms AR-15 CM4 Forged 5.56 Stripped Thermal Fit Upper Receiver

Our forged upper receivers are a great complement to our forged lower receivers. The thermal fit inner dimension measures at .997 -0.0/+0.001" and requires the application of heat in order to provide a solid mate to the recommended barrel extension. By heat we mean more than Granny's hair dryer.-For Use with M4 Barrel extensions-Assembled Upper Receivers come with ejection port cover and forward assist installed-Made in America on American-made machines*** We recommend gunsmith installation for all of our parts. We cannot warranty items damaged by improper installation.