I think the report, as we've gotten it from Tony, is that the proof house believed it had been fired with an obstruction in the barrel at some time in the past, not that it was fired by the proof house with one in it. I can't see how it would be readily possible to find the residual damage from an obstruction, especially when dealing with a pitted barrel, without measuring and mapping every square inch of the barrel and checking the thicknesses and then figuring where there might be a defect. As I understand it, the proof house's job is to check the gun to see if it functions, put their extra-strength shells through the gun, see what happens and, if it passes, stamp the proof stamps on the gun and make the appopriate record entries and reports. Not their job to be gunsmiths. I also think that the presence of pitting, which I recall was both Tony's and the proof house's big concern, may well have captured everyone's attention such that any bulge or defect which might have otherwise stood out was not noticed.
But that's just my take on the situation.
