What is a reamer die, and what is it used for?
An example: "RCBS 7MM-08 REAMER DIE". Graf & Sons has some listed as close-outs, and I'm curious as to what they are.

Thanks,
Washougal Chris

I think it is for reaming the necks inside.

A reamer die is used to enable reaming the inside of the neck, rather than neck turning the outside. It's basically a FL sizer with nothing but the hole in the boss. They are usually provided with the proper size reamer barely undersize to the boss, which you put into the boss above the mouth of the case. It's guided into the inside of the neck and enables the reaming with the "guide", the boss, to a very uniform thickness.

They are commonly used for wildcats that are formed from larger and longer parent cases where the body of the parent case is left as the neck. Since the body of a case is usually much thicker than necks, the reamer sizes the walls properly and leaves a good finished case.

It's likely those 7-08 dies were common before the cartridge was legitimized and they were necessary to thin down the walls of either '06 brass or even 308 brass.

Thanks for the explanation - I think I've got the picture now!

Washougal Chris