100 Straight Choke and Barrel Micrometer 4 Gauge Regular Set

This precision tool shows you to check all the critical dimensions that make a shotgun pattern well. Measures choke, bore diameter, chamber and forcing cone dimensions. Accurate to .001 of an inch. This 4 gauge set includes 12, 20, 28 and 410 and comes packaged in a solid oak case with solid brass hardware. Comes with instruction and extensive information for American and foreign guns.