.300 RUM, Elk, 225 yards, perfect side shot, well placed hit, Hornady GMX. Complete pass through with evidently no expansion.
I would say this is a perfect example of too much gun for the game/range. Well, specifically too much bullet.  Animal was tracked over a mile before it was located laying down… still breathing, still bleeding. The bullet had torn through both lungs and a ventricle of the heart, but not much actual damage. Without expansion, there was very little shock effect… almost no blood-shot tissues internally, and the exit wound looked like maybe a .40 caliber hole.  The hit was observed, clean, and animal was able to run away without so much as a limp.
Take the same situation, same animal, same range, same gun… and load the SST bullet instead of the solid, or a classic Sierra Game King, and I bet that beast would have been dead right there… because that’s what I’ve witnessed before. Bullets that open up faster will deliver more shock, and that is what’s going to put the animal on the ground. Roy Weatherby discovered this many decades ago, and evidently this is a lesson we are still learning.