Off the top of my head;

I'm not familliar with the Lancaster with which Speke had his "accident"; However Samuel white Baker's rifle "Baby" is well known and described in his interesting book "the Albert Nianza". Some of his exploits are described in Richard Akehurst's book "Game Guns and Rifles" He relates how Baker "blew up" a buffalo with an exploading bullet, etc. Good luck in your quest for some of this wonderful African lore.

Best,

Mal