The sideplate, frame and yoke got the so-called "soft fitting" numbers early in the production process. They were meant to identify associated parts of a specific firearm that would be separated later to permit further assembly work on major parts. When all parts for a particular handgun were marked with the serial number for the gun and given their final assembly, the soft-fitting numbers became irrelevant. As the numbers had no long-term importance, they didn't need to be more than a few digits long; these temporary numbers could be repeated without confusion once the last gun to use those numbers was finished and sent to inventory.

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David Wilson