If you will carefully look at Parashooter's original posting you will notice there is a small triangle "flag" by the .4601 head diameter. Then check the notes at the bottom of the drawing. The flag note indicated by the triangle says that the .4601 is a reference dimension. That means the dimension is derived from other toleranced and some times basic (untoleranced) dimensions on the drawing.
IOTW discussion of the .0001 difference is a time waster.
The .4601 is provided for reference only and is not an inspected dimension.