We claim the ornamental design for an end cap of a ball bat, as shown and described.
FIG. 1 is a side, end perspective view of an end cap of a ball bat of the present design;
FIG. 2 is an enlarged side, end perspective view of the end cap of the ball bat of FIG. 1;
FIG. 3 is an end view of the portion of the end cap of the ball bat of FIG. 1;
FIG. 4 is a side view of the end cap of the ball bat of FIG. 1; and,
FIG. 5 is a cross-sectional view taken on line 5-5 of FIG. 3.
The ornamental design that is claimed is shown in solid lines in the drawings. The broken (dashed) lines shown in FIGS. 1 through 5 are included only for the purpose of illustrating environmental elements and break lines, and form no part of the claimed design.