is Carbon spot excess gap?

[thomashoward]

What makes the carbon spot on the cylinder flat by the air gap. I get this on a Model 66, but what I would like to know is this natural (normal) or is there something wrong that makes it do that?
I don't see that on my 27 or 19

 

[Gun 4 Fun]

That's normal. Anytime you have thousands of PSI being forced out through a small gap, and deflected by the frame, it has to go somewhere, and that is back over the cylinder as well as out to the sides.