I have 525gr gcfn hard cast I would love to see testing done with
I used to do a fair bit of elephant hunting. One trip, as a favor to a fellow who wondered if a 45/70 loaded to about 1450fps and using 525gr gas checked hard cast would kill an elephant, I loaded some of his bullets in 458wm cases at 1450fps using H4895, iirc.
After I killed an elephant I shot his loads into the dead elephant from the front, as if I was taking a frontal brain shot, but from a slightly different angle than my shot which killed him. (An elephant's head is made up of different types of bone, from rock solid and able to turn, bend or destroy any solid - which is the type of bullet used on elephant, for penetration- to honeycomb filled with air or a mucous like fluid. The brain is surrounded by homey comb, with a thin shell of hard bone holding the brain.To brain an elephant you must choose a POI leading to the brain through primarily skin, muscle amd homey comb, no thick hard bone. Distance from POI to brain can range from about 10" to maybe 4', depending on the height of the elephant and how it is holding it's head at the shot.) The frontal angle for the shots made with the 45/70 type load were made as if the elephant was about 15yds away and looking at the hunter, which was typical for my elephant hunting. Maybe 30" of penetration required, no hard bone except for the thin brain pan. All of the bullets made it into the brain, but none made it whole, all broke, with angular facets to the breaks. None exited the back of the brain pan.
Moral of the story: I wouldn't want to hunt live elephants with the 525gr hard casts, and I don't think they like velocity. I suspect they would have done better, as far as staying together, at slower velocity. Or perhaps a softer blend (I don't cast bullets, but these seemed "too hard" and we're brittle as a result.)
Also, fwiw, I killed one 250lb ish boar with a 500gr Woodleigh .458" soft point at about 2050fps. Through and through no issue with the plate on either side. Quarter size exit, with a good spray of blood, etc. Range was maybe 25yds. He kept running, second shot was low and broke his front legs and he went down. Dead when we walked up.
I know a couple of (former?) elephant hunters who live in TX and use their .458" rifles for hogs to keep in practice. They report excellent results with the 350gr .035" jacketed Hawk bullets, as well as the 350gr Hornadays and Woodleighs.
JPK