All forged cranks are hardened to some degree.Crank shaft shops say the depth of the harness varies and often the manufacturers were sloppy about it.If the original engine manufacturer listed .030 as the maximum oversize that's a message about crank durability.
Many guys turn cranks well beyond the manufacturer limits,.060 bearings are made for GMC and Chevy I believe.Sometimes it's not a problem and sometimes it is.
A friend lost a crank in a modified GMC 270.A reputable crank shaft shop told him the .030 crank was only hardened to about .015..Loss of hardening can lead to wear and cracks,especially in a modified engine.Sending out a crank for treatment is expensive insurance.
