The RCBS 22-250 Remington Precision Mic is an indispensable reloading tool that determines chamber headspace and bullet seating depth with precision to 0.001 inch. This professional-grade measuring instrument provides spot-on SAAMI tolerance readings by measuring from the datum point on the case shoulder to the base.RCBS 22-250 Remington Precision MicMeasures chamber headspace and bullet seating depth to 0.001-inch accuracyDatum point measurement system for precise SAAMI tolerance readingsEasy operation with just a few twistsExtends brass life through accurate measurementsEssential for reloaders seeking safe accurate loads and maximum brass longevity. This precision tool ensures consistent reliable ammunition performance for 22-250 Remington cartridges.