This tool was designed to make life easier for the advanced shooter and re-loader by allowing precise measurement of ammunition, case, and chamber headspace. With this information, the shooter/re-loader will be able to fine-tune clearances and fits between his ammunition and chamber, with resultant improvements in accuracy and case life.

The primary functions of the Comparator are:

1 - Measure headspace of factory or reloaded ammunition.

2 - Quantify chamber headspace by measuring headspace of a fired case.

3 - Ensure minimal shoulder set-back when setting up re-loading dies.

4 - Compare base-to-ogive length to ensure consistent bullet-to-rifling relationship.

In addition to the Dial Indicator and Stand, the Comparator is supplied with Datum Blocks of precise inside diameter and length. These are used in conjunction with the supplied chart - “Cartridge List” – to determine actual headspace of factory or reloaded rounds, as well as fired cases. By measuring headspace of a fired case, the shooter can come very close to knowing the headspace of the chamber in which the round was fired. This information can be useful if he has several rifles in the same caliber and wants to know if the same re-loads may be used in all of them, or if one has significantly different headspace than the others and should use re-loads made with a different die setting.

Finally, reloaded cases last longer and locate more consistently within the chamber with minimal resizing – you don’t want to push the shoulder back more than necessary for proper chambering. This is also true of rimmed and belted cases and the Cartridge Comparator provides a means of setting your dies to achieve minimal re-sizing.