What does a shotshell checker measure?

A shotshell checker is an essential tool in ammunition reloading and assessment. It is specifically designed to measure the precision and overall quality of the shotshells, including both factory-produced hulls and reloaded shells. By ensuring that the dimensions of the shells conform to the appropriate specifications, a shotshell checker helps to identify any irregularities in the length, crimping, and overall adherence to standardized sizes. This ensures consistent performance and reliability when firing these shells.

The other options do not capture the primary function of a shotshell checker. For instance, while measuring the pressure of the load is crucial in ammunition testing, it typically requires specialized equipment that assesses the pressure generated during firing rather than just analyzing the shell itself. The weight of the shot is also important for performance but is not the main focus of what a shotshell checker evaluates. Finally, measuring the diameter of the bore pertains more to firearm specifications than the shells themselves, as the bore diameter helps determine which shells will fit correctly in a specific shotgun. Therefore, option B accurately reflects the role of the shotshell checker in maintaining the standards of shotshell manufacturing and reloading.