[T. O'Heir]

"...to just visually inspect..." Only for serious wear. You won't really see anything otherwise. Nothing to see with over heating.
And 'shot out' is a relative term. What is shot out to a serious competitive target shooter like a bench rest guy(who thinks in terms of 1/10" or less groups.) isn't to a hunter.
Headspace is checked with headspace gauges and nothing else. No bits of tape, wires, empty cases or chewing gum. Slugging the barrel checks its inside diameter across the grooves. Tells you the calibre and barrel diameter, but not much else.