Thread: Ridge in once fired .303 brass

A collett die has to move the brass from a larger diameter to a smaller diameter and the brass has to go somewhere and that is in the form of ridges. There should be three or four depending on the number of slots in the die. It can be eliminated by first reducing the neck in a full length sizing die or even a neck sizing die. The really good benefit of a collett die is they will true the inside of the neck and all cases regardless of the neck wall thickness will have exactly the same internal diameter giving the best neck/bullet tension result apart from neck turning.