Has anyone here shot an animal with this bullet as large as an ellk or larger?
How did the bullet perform?

The bullets are Hornady 158 gr. XTPs recovered from a black wildebeest I took with a 357 Herrett.

Used one on a 150-200lb hog a few months ago, entered and exited. Lots of blood loss and big holes in and bigger out

I shot a white tail at very close range in a corn field several years ago with a 300 grain .429 xtp with a near max .44 mag load of W296. It was a jump shot, 15 feet or so, hit her in the hind end while running away and got very little penetration. The bullet looked like a piece of bubble gum. It hit a hip bone and bounced off iirc. Luckily I got a broadside shot a few minutes later when she was looking for me and put her down. That experience initiated my switch to hard cast lswc.

Yup, treg, penetration, not expansion...... You already have diameter, now you need to make sure your bullet will make it to the vitals. For that reason, I use hardcast bullets exclusively..........