I have never seen, much less shot, a bongo. However, my friend, Professor Dr. Hans Schabel, took this specimen on a recent hunt in the Central African Republic. He had a choice between a Mauser in 6.5X55 and a BRNO 602 in .375 H&H with Nosler ammunition. Since the shot was taken in an open clearing, he chose the Mauser. The bongo went about 100 yards before expiring.

I used a .375 H&H for my two eland and one greater kudu, which I suppose correspond roughly in size.