Maaate! You gotta get the books and have a read! "Karamojo Safari" would probably be the best place to start since it describes the technicalities of setting up and conducting an extended ivory-hunting safari.

Bell actually dissected an elephant skull and made quite detailed drawings of the proper angle for the brain-shot. In his book "Wanderings..." he devotes whole chapters to the brain-shot and the body-shot on ele. Pondoro Taylor also shows the position of the brain in a front-on photograph of a dissected ele head in his book 'African Rifles and Cartridges'. Must have been an enormous job chopping the entire front off an elephant's head with hand-axes, but I guess their lives depended on knowing where to place that tiny bullet. (Besides, the 'boys' would have done all the chopping!)

NitroX:
You were going off-line (or something!) as I tossed up my post last night, so I had a couple of stabs at getting it to stick before surfing off into the distance.... Feel free to delete any accidental duplicate posts in the future.