The ornamental design for a securing device for an autoloading handgun, as shown and described.
FIG. 1 is a front, side and top perspective view of a securing device for an autoloading handgun, showing my new design;
FIG. 2 is a side view thereof, shown in association with an autoloading handgun and padlock, both shown in phantom outline and not part of this invention, the unshown opposite side being of identical appearance;
FIG. 3 is a front view thereof, the unshown rear view being of identical appearance;