I find another pics of non adjustable rear Arty sight. To me this one (V notch) looks pretty centered inside it's recess.
And this one too:
Wondering weather was it a reason for of-center V notch on that Persian or it was just a sloppiness in QC department of DWM. Another fact is that among these three 1917 DWMs we have 3 different rear sights configuration. Hmmm...