Phil,
The only 500-grain .458 Partition I've seen used in the field was started from a hunting partner's .458 Lott. It hit a Cape buffalo just under the chin at around 40 yards, as the bull raised its head to look in the direction of the slight noise it heard. The bull collapsed at the shot, nose down, because the bullet had broken the spine, then (as far as we could tell during the field butchering) ended up somewhere in the back half of the bull. It wasn't found , so have no retained-weight stories to tell.
