You might be able to make a plug to cover the grips bolt hole if you can find a hardwood dowel the diameter of the hole. Cut a length long enough to entend into the grip about 3/8 to 1/2" and extend out far enough to clear the entire hole. Drill a small hole down the center of that short dowel and insert into the grip. Sand the dowel down to the contour of the grip. The smaller center hole allows you to insert a small hooked awl into the plug and pull it out when needed. Ideally, if you still have the remainder of the stock you would use a plug cutter of the correct size to cut the dowel. Then it would match the rest of the grip when staining.