What 3DMike said, but for me its totally about being "pukka".

Rechambering a British .360 double rifle to shoot an exclusively European cartridge like the 9.3 is just not pukka.
A vintage Brit double so-rechambered would simply give me the sh!ts every time I took it out of the safe.

Similarly, a Krieghoff double in .360 No.2 would be anathema...

Just my 2 cents worth, can't help the way I'm wired.