Back in the dim and distant their was a set of skirmish rules (possibly Donald Featherstone) and I recall all wounds from a Martini Henry were upgraded to severe - unlike other weapons, to reflect the stopping power it possessed.
Having personally fired a Trapdoor Springfield from 1884 into concrete cinderblocks, I can corroborate the penetrating power of big-bore black powder rifles.
The widespread use of dum-dum bullets in the colonial wars also added to the carnage ... those wounded Zulu's at the end would've looked a LOT bloodier and messed up.