The Lee auto Prime hand priming tool is a great tool for the handloader wanting to Prime each brass case by hand. The Lee auto Prime utilizes special shell holders that will only fit the auto Prime, they will not fit in a reloading press. There are twenty different shell holder sizes to suit the needs of all reloaders. Auto Prime shell holder utilize the same number as Lee Universal shell holders and will fit the same cartridges. .17 Rem .204 Ruger .223 Rem.