9,3x64,
I have included the .300H&H within the European hunting calibres as, even if not using the metric system, the British Isles are geographically part of the European Continent. Geography recognises seven continents: Africa, Antarctica, Asia, Australia, Europe, North America and South America, and not an eighth one that would be the British Isles; I often tease my British work colleagues about this undisputed fact and - even if their sense of humour is great, they don't always like it. I realise that I have forgotten the .375H&H in my above list; the Brits have produced in the early XX Century a wealth of good hunting calibres but I have only listed the ones that are still more or less widely used nowadays.
Louis