M1917 Tool

Just got a photo from a M1917 - never seen this before:
Attachment 116059

That sure seems a lot more convenient and precise when doing a bunch of them on the line! My Winchester is fairly centered, but my Eddystone is way off to the left to get zeroed. It's a distracting sight picture because it is so much closer to one protective ear than the other. Changing to a front sight where the ears move with the blade was one of the more important improvements in the adoption of the M1.

So, what is that? Not an M1917 barrel - perhaps a jig to set the height of the front sight insert - although there was a selection of front sight insert heights - so perhaps a factory jig to set all the front sight inserts to same height to accommodate differences in the front sight carrier height?? Maybe not all the "same" height, but that eccentric would seem to indicate to a plus or minus value?? I guess I do not get the comment in Post #2 - I do not see how that has anything to do with setting that sight insert left/right between the protective wings?

At first observation, with no other description, I was thinking it used a wheel as a wedge to move a front sight over. Apparently not.

Gauge to measure the height of a sight from the center of the bore???