If you wonder about how a .440 or .445 round ball will perform on a deer, go shoot a rabbit.
No, I'm not kidding. If you were taking a head shot on a bunny rabbit and accidentally dropped your sight picture a smidgen... you've got a mess to deal with and very little meat to take home.
Yeah, been there, done that. Incorrect follow through when taking the shot.
The bunny went in various directions. Kinda like the Yucatan with Chicxulub.
Imagine that effect on a deer's heart and lungs.
You just have to put Chicxulub where it's 'sposed to go.