Sounds like a good time to start the fine tradition of Re-Loading your own ammunition! It comes out cheaper if you shoot a lot, you can fine tune a round to your own personal rifle and trust me, every single rifle made is different to an extent. you can get several bullet brands and roll a few differently for each lot for accuracy testing. Once you get a load down that your rifle likes the best, you can then test out the performance level on terminal ballistics on an animal. Accuracy always takes first place with ANY round. If you don't put it where it needs to be, no amount of "magic" will help.
Those bullets look like they performed exactly how they were designed. Not over expanded or anything of the sort. Must have been one tough a$$ Muley.