Handling damage produces caps with dents, flattened thread crests and bent pins. The instinct is to reject on sight, and the instinct is sometimes wrong: a dent on a non-functional surface of a cap that still gauges correctly is a cosmetic issue, while a barely visible flat on a thread crest can be a functional failure.
Gauge first. If the cap passes its go and no-go members and the contact-making check, the dent has not affected interchangeability. Then assess the dent itself: is it on a contact surface, does it break through any coating, and could it trap moisture or create a sharp edge. A dent that satisfies neither functional nor safety concerns is cosmetic.
On the thread flanks, because the gauge may still pass while the contact area in a real holder is reduced, which raises contact resistance and temperature. On the shell where it meets the holder skirt, because that is where the cap centres itself. Near the seal, because a deformation there can crack the cement bond.
Decisions on marginal parts should be recorded with the gauge results and a photograph. Without that record, the next inspector faces the same part with no precedent, and the outcome depends on mood rather than on criteria.
