We agree; most likely completely. I just did not use enough words to say it all. I too shot flat point "hard cast" meaning heat treated wheel weights out of the 44 mag through both front shoulders of an elk. That bullet however had both antimony and arsenic to make it tough and still was likely less than 16-18 BHN. We all shot "hard cast" out of the 44's and 45's back in the day. Fact is they were not all that hard. Secondly their shape helped them sustain their direction and integrity while in the elk.
Look at the length of the 250 SW 44 or 45 caliber and compare it to the 400 - 500 .458 pills. The longer the bullet, the more it is likely to bend and then deviate all other things equal. Lastly, a 250 grain SW 44 can turn about in a game animal and you will likely never know as it goes base first just as well as it goes point first.
Ross Seyfreid shot a tremendous about of BIG game with the flat point cast out of big revolvers. Some of those were very hard bullets. The last article I remember reading of his was something like, "In search of the perfect bullet." It was about casting a hard body and s soft nose on those revolver bullets.
I will say my preference in a 458 cast bullet would still be for tough and softer than a hard as hubcaps linotype bullet, but indeed, it is at the end my preference. Anything I shoot at game will have as big of Flat point as I can load and feed for the same reason we all shot them out of the revolvers.
Thank you for adding to the narrative!