Used on various models like the Champion series.

You must remove the grips to find the full serial number, which often includes a critical letter prefix not visible on the outside.

Based on W.E. Goforth’s authoritative research, the serial number's format often reveals the production era.

Visible only when the action is open and the cylinder is removed. The Iver Johnson Serial Number Database Guide

To get an accurate reading, you must look in three primary locations: