Back with more pictures.
I spoze it's possible that someone retro-fit an earlier style sideplate & block for some reason. Here I tried to show the sideplate fit.
Does the assembly number(?) on the sideplate provide any clues?
Here da innards, could not get a clear focused image to save my neck.
More on the front site:
Height from bottom of barrel to apogee of halfmoon/point of tangent, best I could judge: 0.862
Width of front sight blade at front: 0.063
Width of front sight blade at rear: 0.096
Widths measured just above the radius from the base.
Upon further review, I don't believe there's brazing involved, since the color of the metal exposed on top of the blade doesn't change. Solder? Whatever it is, even under my C.S.I. style magnifier/lamp I couldn't see any seam nor color transition.
ETA: Barrel length is 3.92 per ancient vernier calipers & similarly ancient eyes.