From the ballistics chart in the 1926 ICI catalogue:

.300 H&H Magnum : 18.5 tons
.450/.400 Jeffery : 16 tons
.450/.400 Magnum NE : 16.5 tons
.450 : 17 tons
.470 : 14 tons
.500/.465 : 14 tons

...and although you didn't ask, the reason everyone likes the .450 No.2 for this kind of thing : 13 tons!

Hope this helps.