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.
1 . An assembly for improving the longevity of a direct gas operated firearm, the assembly comprising:
a cam race configured to be secured into a recess disposed in an upper receiver wherein the cam race comprises an elongated backplate having a raised portion wherein the backplate is configured to be fastened into a counterbored portion disposed in a sidewall of the upper receiver such that the raised portion extends through an opening in the sidewall and further wherein the counterbored portion is disposed on an exterior of the sidewall, such that the backplate is fastened onto an exterior of the upper receiver;
a slide face of the cam race for supporting a cam pin in sliding contact;
threaded holes positioned along a length of the cam race; and
fasteners for engaging the threaded holes to secure the cam to the upper receiver.
2 . The assembly of claim 1 , wherein the counterbored portion is disposed on an interior of the sidewall, such that the backplate is fastened onto the interior of the upper receiver.
3 . An assembly for improving the longevity of a direct gas operated firearm, the assembly comprising:
a cam race configured to be secured into a window disposed in an upper receiver wherein the window extends through a sidewall of the upper receiver;
a slide face of the cam race for supporting a cam pin in sliding contact;
a corner surface for providing a hardened edge of a cam pocket of the upper receiver;
threaded holes positioned near the window; and
fasteners for engaging with the threaded holes to secure the cam race in the upper receiver.
4 . The assembly of claim 3 , wherein the window is configured to receive the cam race in the form of an insert that positions the slide face and the corner surface inside the upper receiver to be contacted by the cam pin.
5 . The assembly of claim 3 , wherein the window is surrounded by a counterbored area that has a front end and a rear end that are configured to respectively receive a front edge and a rear edge of the cam race.
6 . The assembly of claim 5 , wherein the front edge and the rear edge are configured to engage respectively with the front end and the rear end of the counterbored area.
7 . The assembly of claim 5 , wherein the front edge and the rear edge have thicknesses that respectively cooperate with depths of the front end and the rear end of the counterbored area 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.
8 . The assembly of claim 5 , wherein the threaded holes are positioned in the counterbored area and are aligned with countersunk holes of the cam race.
9 . The assembly of claim 8 , wherein the cam race is retained in the counterbored area by fasteners being inserted through the countersunk holes and tightened into the threaded holes.