I got the Westley Richards in hand yesterday and did a chamber cast. I don't think the 30R Blaser will work for this conversion. My chamber differs from dimensions in Cartridges of the World, as I'll explain.

COTW lists the .400/.360 head (base) diameter as 0.483". That prompted me to think the 30R Blaser would be a perfect fit at the COTW dimension of 0.480" (actual measurement by TN_LongHunter at 0.478").

My chamber cast reveals a base diameter of 0.473" - too small to accommodate the 30R Blaser.

Another disappointment is the rim thickness of the Blaser case. The Westley Richards cartridge employs a stout rim of 0.060" to 0.063". Mine is fully that thick, if not a little more. The Blaser rim, at 0.053" is fully 0.010" too thin, which will invite headspace problems.

Oh well, it was a marvelous idea - on paper!

Don, many thanks for going to the trouble of measuring that case for me.

I guess I'm stuck with Bertram.

Best regards,
Curl