The ornamental design for a riflestock, as shown and described.
FIG. 1 is a right side elevation view of a rifle stock attached to a firearm showing my new design;
FIG. 2 is a left, rear, bottom perspective view of the rifle stock of FIG. 1 with the firearm omitted;
FIG. 3 is a right side elevation view of the rifle stock of FIG. 1;
FIG. 4 is a left side elevation view of the rifle stock of FIG. 1;
FIG. 5 is a rear elevation view of the rifle stock of FIG. 1;
FIG. 6 is a front elevation view of the rifle stock of FIG. 1;
FIG. 7 is a top plan view of the rifle stock of FIG. 1; and,
FIG. 8 is a bottom plan view of the rifle stock of FIG. 1.
The broken lines showing portions of the design in all figures is included for the purpose of illustrating environment and unclaimed features and forms not part of the claimed design.