I claim the ornamental design for a carbon fiber firearm rail, as shown and described.
FIG. 1 is a perspective view of a first image of the carbon fiber firearm rail showing my new design;
FIG. 2 is a bottom view of a second image of the carbon fiber firearm rail;
FIG. 3 is a top view of a third image thereof;
FIG. 4 is a top view of a fourth image thereof, with the broken lines of the screws for the purpose of illustrating the environment, wherein such broken lines form no part of the claimed design;
FIG. 5 is an end view of a fifth image thereof, with the opposing end view being a mirror image thereof;
FIG. 6 is a side view of a sixth image thereof, with the opposing side view being a mirror image thereof; and,
FIG. 7 is an environmental view of a seventh image thereof with the broken lines of the firearm for the purpose of illustrating the environment, wherein such broken lines form no part of the claimed design.
Broken lines shown in the figures represent unclaimed portions of the carbon fiber firearm rail.