The RCBS Precision Mic for .270 Winchester is an indispensable reloading tool that allows reloaders to determine chamber headspace and bullet seating depth to 0.001-inch accuracy with just a few twists.RCBS Precision Mic .270 WinchesterMeasures chamber headspace and bullet seating depth to 0.001-inch precisionMeasures from datum point on case shoulder to base for accurate readingsProvides spot-on SAAMI tolerance measurementsHelps create safe accurate loadsExtends rifle brass life through proper measurementEssential for serious reloaders seeking maximum accuracy and brass longevity this precision instrument ensures consistent safe ammunition that meets exact SAAMI specifications for .270 Winchester cartridges.