Smith & Wessson 36-1 numbers and markings

[Tommy Gun 1256]

I have a 1976 S&W 36-1 Chiefs Special that has numbers and markings under the grips on the frame (see picture). I'm hoping someone can tell me what these mean. Any help will be much appreciated. Thank you.

 

[bobsguns]

Proof marks made when inspections are completed at the factory.

All guns have them in one way or another, at least metal framed ones.

 

[Tommy Gun 1256]

Great information. Thank you.