I have now talked to WR and the owner of the rifle.

The owners father bought the rifle brand new and is according to Westley Richards chambered for .318 WR Square shoulder. WR knew they have told customers in the past to use regular .318WR ammuntion, but would now leave that choice up to the customer, because of the possible danger of case rupture.

So.. What to do now?

I will inform the owner to get custom dies, hang it on the wall or continue to hunt with the factory ammunition as he has done the last 20 years. I supose its up to him...

As for chambering a fired case... I remebered wrongly. It is possible to chamber used brass, but it locks very, very hard.