7,9mm to 7mm cases etc.
The relative position of the 7mm case shoulder is slightly furether back tahn the 7,9mm case shoulder...so full length sizing is the best way to go, and you can even adjust "headspace" especially for some rifles of the pre-1920s era, which have slightly different chamber specs from the more modern ones.
I always size cases "to fit" the chamber, rather than just "Size down to shellholder" method.
This also prevents early case failure as well (over re-sizing and case stretching)
The other thing to remember is to Anneal the cases after sizing (neck and shoulder). The reduction from .323 to 284 creates a lot of internal metal streewsses, which if untreated, will result in "age cracking" sooner rather than later (ie, split necks and shoulders.)
Projectiles...buy them, they are cheap enough. A bullet reduction set-up from Corbin or other maker could cost you between $500 and $1000 for the dies, and a small hand press, and well near $4-5,000 for a Hydraulic press. And the jackets would be loose, and probably deformed as well.
It would be cheaper (relatively) and more effective, to buy jackets, core lead and swage your own... or buy them.
Regards, Doc AV
AV Ballistics.