We supply these custom grade 5 shoulder bolts to our long time automotive customer with recurring annual blanket purchase orders, typically with annual usage ranging between 20,000 and 25,000 pieces.  They are domestically manufactured to a grade 5 standard with commercial zinc, bake and clear chromate finish.  The shoulder measures .40" in diameter by .50" in length, with 5/16-18 thread rolled the balance of the screw.  The overall length is 1-1/4" underneath the head.