Prime

From GunCounter

The process of installing a new primer into a case, after first depriming the case as part of the reloading process.  Almost every model of reloading press includes a mechanism for performing this function. When using a progressive press, priming is performed automatically as the press operates, but the mechanisms included in most single stage presses are slow and cumbersome, so many reloaders instead use a dedicated automatic priming tool when using a single stage press.