I wouldn't mind seeing a photo of the left side of the subject 642-1. This is just my curiosity regarding whether the subject 642-1 actually has the "magnum" type frame with the elongated cylinder stop/limiter.

As I remember, when the 642-1 and 442-1 came out, the 642 version had the +P marked on the barrel but the 442 version did not (just a comment and likely has no significance to the OP's subject). I could see how a non+P marked barrel could have been fitted to the OP's 642-1 and perhaps this might make the OP's gun extra-rare, but not in a way to make it more or less valuable.

FYI, my 642-1's barrel is marked with the info all on the left side (w/+P), and is blank on its right side, unlike the OP's pic.

My last comment is also my observation in that most JHP self-defense .38 Special ammo is being made & sold only in the+P variant. I don't see much, if any, non +P .38 Special ammo being made or sold at all, and not because of the current Covid/political reasons of ammo being hard-to-get/find.

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