Redding Trim Dies allow you to file trim your cases without unnecessary resizing because they are made to chamber dimensions. Other manufacturers use sizing die dimensions, forcing you to full length resize when trimming. For case forming and necking brass down from another caliber, Redding Trim Dies can be the perfect intermediate step before full length resizing.Notes: These trim dies allow you to file trim your cases without unnecessary resizing because they are made to chamber dimensions.This die requires an extended shellholder available from Redding.Form die must be purchased separately.