It is important to understand the die sizes that fit your caliber before you select your dies. You can achieve a perfect match between case and die by using the correct caliber specific dies. However, it is also important to understand the die that fits your case. Not all neck size dies can fit in your standard sizing die housing. Therefore, you need a sizing die or full length die that can fit in a standard sizing die housing. For that reason, many people choose a sizing die in addition to a chambering die - knowing this they can convert their full length die set to a half-length rather than full length die set - using a sizing die alone. However, a full length die set increases the number of die sets needed - and accuracy - for reloading cartridges of different case calibers.