Set stock diameter to 1'' and touched X to side of stock and then set zero in Mach, also set zero with dial indicator.
Did a G54 X0 and the dial reads .002'' under. So 66 version is .0035'' under with that command and 57 is .002'' under. Better
Now set stock DIA to .995 and touched X, did a G54 X0 and the dial reads .0045'' short, so better than version 66 of .005'' but not by much.
if I do individual steps of .100'' so G54 X+.9, G54 X+.8 etc... and work my way in, then each is bang on correct.
Cutting test: