If your bolt is bottoming out on a concrete install application, or you have laid your panel flat against a solid surface, there is a fix. You can use an F436 washer as a spacer in between the bolt head and the hold to get the tightness you need. It may require multiple washers. This typically occurs when the concrete anchor or the panel wasn't installed correctly. Note: This solution works as long as the washers don't raise the bolt head to a level where it protrudes more than 1/8" out of the hold.