5matl steel per ams 6440; hardness per rockwell c55 min and c58 max; 2.108 in. Min and 2.128 in. Max long; 3.7540 in. Min and 3.7548 in. Max od; bore 0.74 in. Min and 0.76 in. Max dia; counterbore 3.382 in. Min and 3.392 in. Max diameter for 1.855 in.