There are always questions about the differences in chip breakers between the Stanley and Sargent vintage hand panes.
The following is a chip breaker comparison for Stanley and Sargent. Sargent-Stanley Chip Breaker differences. This comparison is for a #4 and #409 size hand planes or basically on the planes with 2″ blades.
This came after a discussion with Mark Webster. He did a nice comparison between a type 5 Sargent and a Type 12 Stanley.
Note the Slot in the Sargent is just slightly higher in the Sargent.
The following is from http://www.hocktools.com/BK200small.jpg showing the dimensions of the Hock chip breaker.
Stanley blades and sometimes chip breakers are often found in Sargent planes as replacements. A Stanley chip breaker will work most of the time, but the nut needs to be back much farther.
Also not a reference from The Sargent Hand Plane Reference Guide for Collectors & Woodworkers – Second Edition The photo illustrates the contrast between Sargent’s oval shaped hole and Stanley squared shape in their respective chip breakers.
Also see tuning the chip breaker. This is probably one of the most overlooked parts of tuning a hand plane.