I've done it with Lee sizer dies and they shot fine - but they were not partitions. Got the idea and basic procedure from a Layne Simpson article. He was taking a 358Norma to Sweden I think and really wanted to use 286grs bullets. He couldn't find any factory ammo in that weight so sized down 286gr .366" for .358 use. Got a moose with it too.
I have only shot targets with my resized 9.3s and I doubt that partions or mono metal designs would resize easily enough. A lead bonded core design might be perfect. Read my experiences doing this with further details linked here - at bottom of this page under heading
"RESIZING HEAVYWEIGHT .366" BULLETS TO .358" -
http://35cal.com/bullets.html
