One piece gage that will check overall length to indicate the need for trimming datum to head length to assure correct headspace and to prevent over sizing. Available for most popular rimless cases. The Cartridge Case Gage was designed with safety in mind and was invented by our founder Sam (L.E.) Wilson in 1935 after a fellow shooter approached him for help in solving a case-separation issue. The gage allows you to see just how much you are sizing back your shoulder on your cases.

This is best done by following the steps below.

Measure a case in AS-FIRED condition. Note headspace measurement
Resize case on current die setting
Then place back in the gage to see just how much you are sizing the shoulder back. This can be measured by using the Case Gage Depth Micrometer
Finally adjust sizing die accordingly to desired shoulder set back.

After sizing your cases there is a good chance the brass will lengthen. The gage will also check min/max case length and will point out the need for case trimming. This is an essential tool for every reloader.

Note: Does not measure body diameters. This gage is intended to be used with fired cases to determine a basis for full length sizing and trimming.