Would someone please tell me which of these descriptions is a Type I, Type II and a Type III? I have a July 1943 M1icon with 1,770,XXX serial. My rifle has a square lock bar rear sight on it.

I see only Type II sights described with having rounded bars and Only Type III sights described with square bars. Do the type II have only short pinions and Type III have only long pinions? If so there are 2 types of Type III, square and round.

I'm confused as to what I need to do. Do I need to change just to lock bar to make it correct?

SA Rear Sight Usage

Rear Sight Short Pinion Flush Nut
Checkered Windage/ Checkered Elevation
Used from start of production to 200,000.

Rear Sight Short Pinion Flush Nut
Knurled Windage/ Checkered Elevation
Used from about s/n 200,000 to 500,000.

Rear Sight Short Pinion Rounded Lock Bar
Knurled Windage/ Checkered Elevation
Used from about s/n 500,000 to 1,009,000.

Rear Sight Long Pinion Rounded Lock Bar
Knurled Windage/ Knurled Elevation
Used from about s/n 1,009,000 to 2,700,000.

Rear Sight Long Pinion Square Lock Bar
Knurled Windage/ Knurled Elevation
Used from about s/n 2,700,000 to 3,900,000.
Information
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