"The results of my shim hardness test is as follows:
First I tested 2 standard shims. One came up at 55 rockwell the
other came up at 48 rockwell, a little variation between them for
reasons I am not sure. Then, I machined 4 seperate shims. Results
are;
Thickness removed / Rockwell
.0025" 41
.005" 41
.010" 35
.015" 29
These shims are only case hardened and I wouldn't recommend taking
more than .002-.003 maximum off the shim if the correct shim cannot
be found. I hope these findings are helpfull. Regards, Peter."