S&W M-64 extra numbers not serial number??

[BN]

A few years ago I bought a used 2 inch M-64-6 at the LGS just because I didn't have a 2 inch K-Frame. It showed signs of being carried but it was in good shape mechanically. It's a round butt, but it came with a set of old beat up square butt magna grips. I put on a set of my favorite Hogue grips and shot it a few hundred rounds. Shoots nice. Mostly it sits in the safe.

Fast forward to last Saturday when I'm attending the Randy Lee revolver class. I took the M-64 to be the gun I worked on in class. As Randy is instructing us on how to inspect the revolver, I noticed some extra numbers on the frame. I had always thought that it was probably a police trade in. Now I'm curious. Does anybody have any idea what they mean. The numbers are very neat and well done. 055 is also stamped on the inside of the crane. A17 is stamped near the serial number.

[fatdog]

I have owned a couple of S&W guns with an extra number engraved like that, not the serial number. Each was a laser engraving. I haven't ever received a definitive answer. My current 645 was originally sold as a BX gun in Germany and the owner brought it home in the 80's, so I wondered if something related to that import/export/PX system could be the source.

So I am interested to hear what insights get shared on this subject.

[FrankB]

My police trade in M64 has the same sort of numbering, in the same area. Maybe it’s done at the factory. 🤷🏼

[BN]

OK, I feel kinda silly now. Every S&W I have checked that has the firing pin in the frame has the same sort of numbers. I thought I might have something special. Nope, just another modern S&W revolver. At least the M-64 doesn't have a lock.

[Brian T]

My two 64-6s have those numbers as well. Perhaps a part number?

[kwb377]

I read somewhere that those are production numbers, meant to match the frame and crane together as they travel through the assembly process.