Body Die
A die that sizes the case body and bumps the shoulder back without touching the neck, useful for separating body work from neck tension control.
A body die works the outside of the case body and sets the shoulder bump, but it has no neck section, so it leaves the case neck untouched. That lets a reloader tame a case body that has grown after several firings, restoring easy chambering, without changing the neck at the same time.
It is a middle ground between neck sizing and full-length sizing: the shooter can size only the neck for grip with one tool and bump the shoulder with the body die when needed. Within a set of reloading dies, it gives precise, independent control over body fit and neck tension.