A telescoping bore gauge is used by placing the gauge within a bore, expanding the telescopic arms until they make contact with the bore walls, and then locking the arms into place at that specific dimension. Once locked, the gauge is removed from the bore and measured separately. This two-step process allows for more accurate and repeatable measurements, as it eliminates the potential for variations caused by the measurement process itself. Telescoping bore gauges are particularly useful for ensuring accuracy in situations where direct measurement within the bore is challenging or impractical.