Collet Neck Sizing Dies are only interchangeable with other calibers if the bullet diameter, case length, base diameter and base to neck/shoulder intersection dimensions are the same. If these dimensions are not the same between the two calibers, they can not be interchanged.
When looking at Ackley Improved cartridges, the standard Collet die for the parent cartridge should work, provided that the base to neck/shoulder intersection dimension has not changed. Most Ackley Improved cartridges have less body taper, and a steeper shoulder angle, but the distance from the base of the case to the neck/shoulder intersection is not changed. There is enough clearance in the collet to accommodate the improved cartridge.
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