The ornamental design for a billiardrack, as shown and described.
FIG. 1 is a top, front, right side perspective view showing my new design for a billiard rack.
FIG. 2 is a top view thereof.
FIG. 3 is a front view thereof, the back view being a mirror image.
FIG. 4 is a right side view thereof, the left side being a mirror image.
FIG. 5 is a bottom view thereof.
FIG. 6 is a bottom, front, left side perspective view thereof; and,
FIG. 7 is a cross-sectional view along lines 7-7 of FIG. 2.
The broken lines that depict notch marks along the top edges of the billiard rack in FIGS. 1 and 2 indicate unclaimed portions and form no part of the claimed design.