Peter,

I measured 10 PH 5c sights. There is a diffrence between the front and rear of .001". Perhaps to take up differences in the receivers as I've work on a few sights that have been "fitted"....didn't keep the info however there was material filed from both mounting loactions in order to fit the sight. Makes sense as all No4's are identical in tolerance. I get similar measures to you. Front .1330" and rear .1320".

Ron