The ornamental design for a slingadapter, as shown and described.
FIG. 1 is a right, top, front perspective view of a sling adapter attached to a firearm showing my new design;
FIG. 2 is a left, front, top perspective view of the sling adapter of FIG. 1 with the firearm omitted;
FIG. 3 is a left side elevation view of the sling adapter of FIG. 1, the right side elevation being a mirror image;
FIG. 4 is a top plan view of the sling adapter of FIG. 1; and
FIG. 5 is a bottom plan view of the sling adapter of FIG. 1.
FIG. 6 is a front elevation view of the sling adapter of FIG. 1; and,
FIG. 7 is a rear elevation view of the sling adapter 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.