what does the number on the crane mean if anything?

With S & W revolvers of certain eras, there is an assembly number stamped on the frame and also on the yoke (other makers refer to the same part on a revolver as the crane). I don't believe modern guns have this. The best you can say is they are factory internal codes that are not decipherable.

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Alan
SWCA LM 2023, SWHF 220

Some models have the serial number on the yoke along with manufacturing process control numbers and others just have manufacturing process numbers there. All the numbers on the revolver not serial number or model number related are process control numbers and inspection stamps. On Nickle factory guns they also have an N on the frame and sometimes on the rear of the cylinder.

What is the difference between a manafacturing process number and a manufacturing control number?

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inyomono

The gun I'm refering to is a pre lock 342PD the numbers are 431.

He is overthinking this. Properly they are referred to as assembly numbers with S&W. This is the generally 5 digit number that is found on the yoke, on the frame, and inside the sideplate. They identify these parts as a set that have been precisely fit and polished as an assembly so the joints match closely and are aesthetically pleasing. During final assembly it is used to rematch these parts that were separated after polishing and are delivered to the fitter as a tray containing sufficient parts to assemble 10 revolvers. It assures the fitter matches the correct yoke and sideplate to the frame they were fit to. Once the gun is put up they no longer serve any purpose. They are not recorded or tracked by this number in any way as would be the case with a "control number".

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Gunsmithing since 1961