OK-

Not really quite sure what you're getting at then.
Eleven thou aint much.
Striking isn't all that happens between the time the worker removes metal and the shooter drops a hammer on a firing pin. But rest assured the surfaces of that metal differ in quality than the meat between them. Two thou isn't much, but it's about right for hard steel and two plus two equals four. That's about right for an account of the surfaces of a barrel, and it's in the neighborhood of more than a quarter of the material present.
Percentage wise that's a fuc'load, and typically alpha case is harder, sometimes tougher (not always) than the parent material. As bluing, blacking, and browning are oxide and -not metal- there's something there to note as well. That stuff tends to be harder than the parent metal as well as having a bulkier molecular structure. The section of a good blacking job is gonna be much thicker than the molar section too.

And eleven thou ain't likely enough from the getgo as far as barrel wall goes either way.
I think the shotgun in question was ruined at the shop and in my -earlier- post had noted the dude who worked on that gun as 'reputable' and did so in quotation mark to entonate sarcasm.
I put your words in quotation marks to note my use of (specifically) your language in your later thread, and my intent there was to salute you on your choice use of language as it had entertained me.

If there's something else I've missed, let me know.