Mike, The 9.3x74R doesn't make a very good case for the Westley Richards version of the .400/360, because the Westley Richards version has a much thicker rim. The little shoulder on this cartridge really isn't enough to provide headspace.

I once had a Mod. 1897 WR single shot chambered in this caliber. Cases made from 9.3x74R were unsatisfactory.

On the other hand, a rifle chambered for the Purdey version of the .400/360 will do fine with cases made from 9.3x74R. The rim thickness is the same.

I have a Greener double rifle chambered for the .400/360 NE, and this is where I get my brass.

I did find necessary the use of a neck reamer. Shoving the shoulder back to the proper position leaves a thick area of neck where the former 9.3x74R shoulder was.

Once formed and reamed, no problems at all.

Curl