US12584703 - Cam race for improved upper receiver longevity
An apparatus and methods are provided for a cam race for improving the longevity of an upper receiver of a direct gas operated firearm. The cam race provides a hardened slide face and a corner surface for a cam pin comprising a bolt carrier group of the firearm. The cam race is configured to be secured into a window disposed in the upper receiver. The window is surrounded by a counterbored area that receives a back plate of the cam race. The counterbored area and the thickness of the back plate cooperate such that the corner surface and the slide face are positioned to receive the cam pin during reciprocal movement of a bolt carrier group within the upper receiver. The cam race is retained in the upper receiver by fasteners that are tightened into threaded holes in the counterbored area.