The ornamental design for a grippingportion of a grill brush handle, as shown and described.
FIG. 1 is a top perspective view of a gripping portion of a grill brush handle showing our new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left side elevational view thereof, the right side being a mirror image;
FIG. 5 is a top plan view thereof; and,
FIG. 6 is a bottom plan view thereof.
The broken lines in FIG. 6 represent the bounds of the claimed design while all other broken lines are directed to environment and are for illustrative purposes only; the broken lines form no part of the claimed design.