Shotgun Wall Thickness Gauge
Used by proofhouses, gunsmiths, and gun dealers to accurately measure barrel wall thickness. Exact direct read-out provides information you can use to determine if the shotgun barrels are safe. Also used to determine if barrel walls are sufficiently thick for choke tubes.  Dial indicator measures in .001' increments.  Measurement range:, 12, 16, 20, 28 gauges.  Blued base with brass fittings, rigid steel construction.