Depending upon the depth of case the hardness could be greater than revealed by a Rockwell tester. Often the point of the diamond on a rockwell machine will break through the case & give a false reading, always softer than actual hardness of the case. There is I believe a D scale which is used on Case Hardened parts. It does require a different penertrator than the normal C scale.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra