Is this normal on a 66-1?

[chief38]

I am only guessing, but it might me a mark left by a jig when they fit the barrel to the frame. I am curious too - someone should give them a buzz.

 

[mstuhr]

67 &10-5

Howdy,
My 67 no dash and 10-5 both have it. The 67 is struck a little harder.
Mike

 

[corgiS&W]

My new [to me] 66 no-dash has it. My 67 no-dash also has one.

 

[thomashoward]

My 17 18 19 and 27 also have it
624 and my 66 do not

 

[girvin02]

I seem to remember reading somewhere that punch marks were random QC testing for Brinnell hardness ? Proper temper of a test specimen by inspection prior to shipment. I've seen a few with punch marks, but not like the one in the pic.

Brinnell testing would leave a perfectly round dimple. The diameter of the dimple is what determines the hardness (the larger the diameter, the softer the metal).

 

[markush]

Both my 80's vintage 27-2 and '69 vintage 37 Airweight have it, heavier on the Airweight's aluminum frame. As girvin02 said, hardness testing would leave a round dimple. I like chief38's idea of a jig to fit the barrel...seems plausible to me.

 

[Texas Star]

Puma knives have a hardness test dimple in the blade, but they measure Rockwell hardness.