Your problem isn’t the bullet, it’s the point of aim and where you’re actually hitting the animal.
You can try all of the above recommended alternative bullets, yet still have the exact same outcome. The ELD-X is not a hard bullet, if it’s not exiting it’s because it’s breaking up in the animal. Having used the 178gr in 308 for a while a few years ago, in the same circumstances as well as longer range, I know for sure that a proper “hilar” or high shoulder shot at close range will drop an animal on the spot. But stray little too far back behind the shoulder, and it’s going to run.
If you’re shooting for the heart, there’s your problem right there.
Spend some time studying anatomy and shot angles depending on how the animal presents. There’s heaps on here about that, search for “hilar” under my username and that’ll start you off in the right direction. It’s vital that the bullet is penetrating through the animal such that after it has passed through the hide/muscle/bone on entry that it’s on course to destroy the front lungs/aorta/pulmonary arteries, if you shoot behind and above that you’re only going to get rear lungs and nothing that will immediately stop locomotion, so off it runs. Not far, but far enough.
Good luck!
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