Ever see this sight notch before?

[Ray Patton]

1938 chamber/S42 toggle marked rebuild,supposedly out of a bunch found in storage in Norway years back,came from an Importer in southern Ohio,bought it as a shooter,don't remember exact price,around $230 or so,any way look at the notch in rear sight,don't know who,why or where fores of who did it but sure helps getting a sight picture.