We claim the ornamental design for the cheek rest for a firearm charging handle, as shown and described.
FIG. 1 is a plan view of the top of a cheek rest for a firearm charging handle;
FIG. 2 is an elevation view of the right side of the cheek rest for a firearm charging handle of FIG. 1, the left side elevation view of which is a mirror image of the right side;
FIG. 3 is a perspective view of the top, right side, and forward end of the cheek rest for a firearm charging handle of FIG. 1;
FIG. 4 is a perspective view of the top, left side, and forward end of the cheek rest for a firearm charging handle of FIG. 1;
FIG. 5 is an elevation view of the rearward end of the cheek rest for a firearm charging handle of FIG. 1; and,
FIG. 6 is an elevation view of the forward end of the cheek rest for a firearm charging handle of FIG. 1.
Portions of the cheek rest for a firearm charging handle shown in broken lines form no part of the claimed design.