Possible barrel bulge

[Big D]

If there is no evidence on the outside, how can it be called a bulge? If the metal yielded for some reason, resulting in a spooned out section on the interior, where did the spooned out material go? Should result in a ridge surrounding the spooned out area. Is it possible the bad area was honed for some reason?

[edgarspencer]

a slight bulge can be visible looking down the bore, and certainly measurable. but only barely perceptible to the touch, but not to the eye on the outside.