These custom slotted lock nuts were manufactured using 4140 alloy steel material heat treated to 28-32 HRC. A 5% taper on the shoulder was required which created some difficulties in modifying the cold heading equipment to meet the required tolerances. The outside diameter was set to 1.00″ and the tapered shoulder reaches 0.75″ at its minimum. Parts were run through black oxide process as the final step in the production process.