The American .25-20 WCF is very close to probably the nicest Rook rifle calibre, a tiny bottleneck round known as the .297/250. This had a true .250" bullet of 56 grains at just over the speed of sound, and is great fun.

Of course the Original Poster lives in Scotland (or North Britain in Victorian times) and so cannot legally shoot deer with a .32-20 because of the minimum velocity law. But a .22-250 is fine....

HB