I'm sure the already answer lies within this forum somewhere.
I may be confusing
.40S&W vs. 9mm frames with
B vs. SA frames (don't have either myself to check), but I thought SA frames were thicker and longer in the frame rails, regardless of caliber. At least this was the case with holster fit... I don't know if that translates into slide fit as well, especially where the Kadet is concerned.
Sorry for probably adding more confusion than helping
-iNJ