Shortly before this discussion degraded beyond my interest and tolerance, I had planned to make a constructive comment as follows:
Somewhere I had read that no 4 legged game can walk or run if either the shoulders or pelvis are shattered. The wounded animal may be able to crawl, but not run to either charge or escape. This has been repeated in many hunting stories. So, as part of my preparation for my first Cape Buffalo hunt, a part of my practice was locating these two bony structures and pulverizing them with a 400 grain Woodleigh solid BEFORE firing my first shot at the Buff target.
As it happened in RSA, my DG PH and trackers led us to the rear of a small group of buff and to within 25 yards of the last of the group. As the PH set up the sticks, I
saw that only the pelvis would be visible after my first shot as the buff was grazing almost directly away from me towards some thick cover. My shot placed a 400 grain Woodie just behind the rearmost left rib and the buff responded with a rearward kick of the left hind foot and began to slowly walk away. My next shot shattered the pelvis
and brought my buff down with a loud crash that shook the ground.
It turned out that my first shot had gone through the heart and though lethal, was not enough to drop the critter to the ground.
Interesting observation, and I'm glad your process worked as expected! The late, great Bob Hagen was an advocate of pelvis shots on elk ("Shoot at the root of the tail," as he put it) and other large ungulates, and others have said the same. I believe Boddington touches on it in his buffalo book, but barely. Other than that, I can't recall any buffalo hunting authority advocating pelvis shots.
I've only tried a pelvis shot on a couple of critters in my whole life, one of which happened to be a Cape buffalo (it was my 3rd shot, he was walking away after taking 2 fatal shots in the heart and lungs). I also happened to miss the bony pelvis on that buff, so the animal did not instantly collapse as he was supposed to.
The funny thing about game animals, DG or otherwise, is that what you visualize as the relevant target anatomy may not be reality. What you think is a solid shot into the pelvis may miss bone entirely, depending on angle etc, and in reality be only a low belly shot. I run into this a lot when I review LE shootings of bad guys, and the postmortem exam and/or autopsy reports afterward. But cops aren't anything like as familiar with anatomy as hunters are, and PH's should be.
