ScopesGuide.com Glossary

Terms that start with C

Calibre is the measurement of the interior diameter of a tube.
In a centerfire cartridge the primer is located at the center of the cartridge casehead and is a separate and replaceable component, unlike that in a rimfire cartridge.
A crosshair, also known as a reticle, is a superimposed shape or image that helps shooters get accurate alignment when using a scope.