I just read that if a Centennial model has 4 screws in the side plate it was made in 1955 or earlier, without the model number stamped inside the yoke area.
My model 40 (no dash) has 4 screws on the side plate but serial number 145xx indicates 1957 mfg.
When was the 4th screw at the top eliminated?
The 4th screw was ORDERED eliminated:
• Eliminate upper side plate screw change order 12/13/55, the 4th screw on New I & New J frames.
But all changes could take months to show up on manufactured parts and guns depending on how many were already in the production process.
What's your source indicating 1957 Manufacture for #145XX? None of my sources indicate that.
So as described in the above posts, the manufactured date of any serial #'d gun OR its parts like a side plate drilled for 4 screws, can be close or several years earlier than its shipped date. Close for popular, fast selling models and much longer periods for slow moving models.
For reference:
15XXX……earliest #'d gun known to me, that's Mod 40 stamped, shipping date unknown.
17,699…..shipped in May 1961, 4 screw, whether Model stamped or not unknown.
22,675…..is the highest #'d 4 screw known, shipping date unknown, whether Model stamped or not unknown.
Hope that helps,
