Sourdough.
If you had used a Wide Flat Nose - non-expanding cast bullet of proper dia. and weight on any game animal, then you would know that, "A solid would be useless." is not always correct.
The difference is in the WFN bullet profile and in trueth, the wound channel and the distance this bullet will travel through a critter is simply awesome. Plus, you don't need 2000fps to get the job done.
It took a big step of faith for me to let go of the many years long thought that it has to be an expanding bullet to put a game animal down, but now that I have been there and done that, personally seen the results and watched the critters reactions, well every thing I read about this type of bullet and it's great effectiveness is true in spades.
So, if we are talking about the typical round nose solids many times used in heavy stopping rifles, you may well be correct, I have not been there and done that and have only what I have read to go by.
However, a heavy WFN non-expanding bullet of good dia. and weight, cast of an alloy that will not shatter on impact IS a different animal by far.
That Wide Flat Nose is the secret, and those bullets gives a wound channel all out of expectation for a expanding jacket bullet shooter/hunter. This bullet has no need to expand, due to the size of the meplat.
One thing that has really surprised me is the hole in the near side hide. Not the little tiny pencil sized or smaller hole typical of the jacketed, expanding hunting bullets, but a hole showing that the WFN bullet is doing it's job from the instant it impacts the critter's hide.
You don't need to take my word for it, there is plenty of info available on the Marlin Owners Forum (check the .444, 45/70 and 450Marlin sections), the Cast Boolits Forum and in the writtings of Randy Garrett - the ammo maker - and on the Beartooth Bullet web site and forum, plus plenty of other sources.
Then, also check out the writings of Veral Smith, of Lead Bullet Technology (LBT) on the web or buy his book on the use of cast bullets for hunting.
Check the web for cast bullet hunts with the 45/70 in Africa as well as the Marlin Owners forum about Afican hunts.
Crusty Deary Ol'Coot