The ornamental design for an open frameholster, as shown and described.
FIG. 1 is a side perspective view of an open frame holster showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a right side view thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof;
FIG. 6 is a left side view thereof;
FIG. 7 is a rear view thereof; and,
FIG. 8 is a left side view thereof, similar to FIG. 6, showing the arrangement of a suppressed pistol in the open frame holster.
The broken line portions showing surface cavities, extensions and through-holes in FIGS. 1-8, and the exemplary suppressed pistol outline in FIG. 8, are shown to illustrate environment only and form no part of the claimed design.