We supply these custom hex shoulder screws to our Canadian customer, with the shoulder measuring .425 +/-.002 by 1.650 +.005/-.000 in length. 5/16-18 thread was incorporated measuring .50" in length including the unthreaded portion before the rolled thread begins. .055 radius hole was then drilled at .102" from the end of the threaded portion. 4340 alloy steel was used to produce the part, oil quenched and tempered at 315 degrees with min. 55 HRC surface hardness required to meet our customer's requirements. The hex head measures .62" across the flats and .36" in height.