I would think the .404 would be fine. I am going back to the Caprivi in 2019 for buffalo and am looking to use a .458 Lott only. I have a 450 grain load (TSX softs and Hydrostatic solids) worked up for buffalo, and I have a lovely 400 grain Woodleigh PPSP load for the same rifle that I anticipate to use on plains game if and after the buffalo is in the salt.

At the end of the day after playing and experimenting with the load development, if during the quest for buffalo, a wonderful plains game target of opportunity appears and I happen to have a 450 grain buffalo cartridge in the chamber, well, I’ll shoot the plains game with a buffalo load and not think twice about it.

The .404 has the power and reasonable reach. Just get lots of practice and know your rifle!!!!