Upper receiver for a firearm

FIG. 1 is an upper perspective view of an upper receiver for a firearm according to my new design;

FIG. 2 is an upper perspective view thereof;

FIG. 3 is a lower perspective view thereof;

FIG. 4 is a lower perspective view thereof;

FIG. 5 is a side view thereof;

FIG. 6 is a side view thereof; and,

FIG. 7 is a front view thereof.

The broken lines in the drawings depict portions of the article that form no part of the claimed design. The broken lines illustrating portions of the upper receiver for a firearm including the plane surrounding the hexagon and partial hexagon recessed features are not included in the claim.