I don't know if Weatherby brass is more available in OZ, but back before the .416 was reintroduced, I used to turn the belts off .378 Weatherby cases and resize them to .416 Rigby. They worked fine in my Ruger No. 1 and as recently as two weeks ago worked fine in my CZ 550. I believe the rim size is a little different, so you may have to use a Weatherby size shell holder.