This is a Redding 303 British caliber Neck Sizing Die only. A neck size die allows the reloader to properly size the case neck just enough to snugly hold the bullet for optimal bullet tension, while maintaining the fire-formed dimension of the case body. Accuracy is increased when the case body closely fits into the chamber. By not overworking the brass, this Redding Neck Sizing Die produces superior accuracy and extends the life of expensive cases. Neck sizing with this die can eliminate problems of excessive head space and align the bullet perfectly with the bore, resulting in better accuracy and longer case life.