Lyman's Ammo Checkers are precision "Go/No Go" gauges that allow a reloader to quickly confirm that their ammunition will fit in their chamber. Gauges are cut to SAAMI (or CIP for non-SAAMI calibers) minimun chamber dimensions. Just drop your loaded rounds in the Ammo Checker, and if the rounds fit into the gauge flush or below the top surface, they will chamber. Specifications: - Type: Single Chamber - Cailber: 300 AAC - Pack Quantity: 1