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?

Welcome aboard from ol' Wyo.

For Centennials, you've asked the $64 question.

Chiefs Specials began the transition from 4-screw to 3-screw in the late '56 - early '57 period.

Centennials (different serial number series than the Chiefs) might have begun around that era, too, but they were slow sellers compared to the Chiefs so they sat in the vault longer. It took longer to deplete the 4-screw stock on hand. Your best bet to know exactly when yours shipped (S&W's only tracking date, because the company didn't track production dates) is to order a history letter. You'll find the form to order a letter in the "Downloads" area of the forum in the menu bar at the top of the page.

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Wrangler of stray Chiefs
Bob

Thanks Bob from Wyoming. I have spent a lot of time in your state....love every inch of it.
I have a pre-34 kit gun (2") with serial number 42xx that leaves me scratching my head. Evidently S&W started a new serial number with this one. Very confusing.

Oh, I'd suggest not scratching your head over S&W models and their serial numbers. You'll wind up like me with no hair.

The J-frame Chiefs Specials began in 1950 with a new serial number series that began with 1, even though serial number 1 wasn't shipped till July 20, 1951.

When S&W launched the Centennial in late '52 it was given a new serial number series that began at 1.

Then in 1955 S&W launched the Bodyguard Airweight and included it in the Chiefs Special serial number series.

When S&W launched the Model 60 in 1965 it also followed along in the Chiefs Special & Bodyguard serial numbers.

They were all J-frame .38 Specials, but for some reason we may never know, the Centennials didn't fit in.

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Wrangler of stray Chiefs
Bob

To add to two-bit cowboy's reply, the new Model of 1953 .22/32 Kit Gun (as well as the .22/32 Target) started a new, completely separate, serial sequence in 1953. That sequence continued into the model number era (Models 34 and 35).

Also, note that the .22/32s were built on the I frame until c. 1961 when they were transitioned to the J frame with the -1 variants.

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Jack
SWCA #2475, SWHF #318

According to the data I have been able to accumulate the serial numbers shipped in the 1957 era are 101xx-108xx! The 145xx numbers were in early 1959. A factory letter is the only way of knowing when your gun was shipped.
jcelect

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,

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Jim
S&WCA #819