Looking at that first shot more closely, that is so unlucky to have gone through what you did. It looks like the bullet went just under the spine on a pretty level path thru. A smidge higher and that animal is anchored on the ground where it stood. A smidge lower and his lungs would have collapsed and he wouldn't have gone far. A smidge further forward and both shoulder blades would have been destroyed and he couldn't be able to run anywhere. Archery hunting this is often called the VOID because there is a pretty large area up there where an arrow can go in and not do enough damage to kill an animal. I can't really recall many instances that I know of where a rifle bullet can pass through any of that area and not provide a kill or at least significantly cripple the animal to recover them. Which I suppose is what ended up happening with you thanks to your perseverance.