The ornamental design for the weapon handguard accessory mounting system, as shown and described.
FIG. 1 is a front perspective view of a weapon handguard accessory mounting system with an accessory rail mounted to a handguard body of a weapon handguard;
FIG. 2 is an exploded perspective view of the weapon handguard accessory mounting system showing the accessory rail and quick-turn fastener;
FIG. 3 is a top perspective view of the accessory rail and quick-turn fastener of the weapon handguard accessory mounting system;
FIG. 4 is a bottom perspective view of the accessory rail and quick-turn fastener of the weapon handguard accessory mounting system;
FIG. 5 is a perspective view of the accessory rail of the weapon handguard accessory mounting system;
FIG. 6 is a top view of the accessory rail of the weapon handguard accessory mounting system;
FIG. 7 is a bottom view of the accessory rail of the weapon handguard accessory mounting system;
FIG. 8 is an end view of the accessory rail of the weapon handguard accessory mounting system; and,
FIG. 9 is a section view of the accessory rail of the weapon handguard accessory mounting system.
The components shown in broken lines in FIGS. 1-4 are for illustrative purposes only and form no part of the claimed design.