No offense to anyone, but I really really want to slow you down on this path towards match bullets for big game hunting. There is a reason that as an elk guide I would not allow match bullets to be shot at animals.
I think we need to back up to find the culprit here. What you experienced is one of those relatively rare “that doesn’t make any sense” moments with a certified big game bullet. These do happen, but they are rare. My godfather was professional hunter in Africa for 50 years. Saw thousands of animals taken in person. He noted that from time to time, a well made, properly calibrated bullet will hit an animal in the right place at the correct angle, and fail to adequately kill the animal for unknown reasons. This is the nature of high velocity projectiles made by imperfect humans. Things will sometimes go wrong and it’s not your fault. It’s not really the bullet’s fault either (well, probably not).
However, a match bullet would do what your bullet did more often. Match bullets are not a great choice on big game because the core is not well bonded to a thinner jacket, meaning when they hit tissue, they often violently expand, and lack penetration. You may here this referenced as uncontrolled expansion (more or less what happened with your bullet; total fragmentation). What some folks are getting wrong in this chat is exactly this: Uncontrolled expansion does often lead to a pretty devastating wound on the animals, and often kills them. Especially when that shot is well placed and especially on weak game like whitetail deer. However when you run the math, it’s a much better idea to have a thick jacketed bullet designed for hunting that has some expansion and is designed to penetrate as far as possible into the animal to reach the vital organs needed to kill it. Those guys who are killing elk with match bullets, I’m not doubting you’re telling the truth. You maybe shot 10 elk is the last 8 years if you’re good at what you do. That’s great! But your sample size is too small to know that those bullets are actually effective over the long run at killing elk. You don’t want to find that out when your match bullet fragments on the shoulder blade of a giant Arizona elk quartering away and basically bounces off of it.
The gentleman above, that notes that he killed a cow elk with a front shot with a .223 and match bullet, I can appreciate a good shot that worked out for you, but to put that on the internet and recommend it to random folks is not a good idea. You and I know that yes, an elk could be killed cleanly with a 223 but no, it’s not the ideal thing to recommend to folks. A rib bone or leg bone of a cow elk could easily turn that hunt into a nightmare scenario. Shot placement is key, lots of us could make that shot work, but it’s not the safe option for a clean ethical kill for most hunters.
OP, overexpansion actually was your fluke problem, and is tied to under-penetration. Your bullet deformed on angled impact with hard tissue (eg bone) and fragmented, slowing it down. The animal was able to survive the transfer of kinetic energy and the fragmented bullet didn’t disrupt vital organs, which is what you need to have happen. Hard to say why this ELDX did that, but that’s the unknown factor I describe above. A match bullet would do this more often, with worse results over a large sample size of animals shot. Long story short: your eldx fragmentation was a fluke, don’t go changing to match bullets that do it more often.