Use a Lyman case length headspace gauge as part of the inspection process on bottleneck rifle cases after resizing and prior to loading. Simply insert a case into the gauge to make sure that it will not exceed maximum or fall below minimum headspace. The gauge will also identify any case that exceeds allowable length. Cases with excessive headspace should be destroyed.

Specifications and Features
Lyman 7832338
.300 AAC Blackout
Checks case headspace
Identifies cases with excessive length
Steel
Weight 8 oz