Respectfully, I have a hard time believing that the hands and minds which could produce the tolerances which make an LC Smith lock up like a bank vault 70-100 years later...could ream a chamber our of whack by that much.
At this point...considering both the feedback of others and my own experience with other makes, is that either:
(A) 1/16th or so was within the tolerance of chamber measure, and/or measures were to the end of the breach rather than the mouth of the lip...such that my gun actually constitutes what hunter meant to be 2 3/4's (B) The gun is 2 5/8's, as intended.
Frankly, as another member stated, using lite loads it likely doesn't matter. So as I use lite loads, I'm in the clear no matter what.
By like I also said...some guys just want to "know." I guess that's me.