Am actually looking for a neck sizer for my .257 Robert's. Gun I inherited has a unique chamber, its not AI, and standard .257 Bob brass/dies don't fit it. Have a bunch of 1x fired for it from the original owner, going to try neck sizing until I can't get away with it, and order a custom die, which I assume will be a few bucks.
Hornady used to sell a 25 caliber neck sizer. Could be used for most 25 caliber rounds. - dan