When i was a teenager my brothers and father and I semi-professionally shot kangaroos on wheat crops. As we weren't shooting them for the chillers, we used all manner of calibres and bullets. Yes they were pretty much all cup and cores.
The difference in reactions to similar hits was incredible, even with the same load, range etc. We mostly shot the shoulders, which aren't all that tough even on the biggest roos.
One large roo shot with a 100g Interlock from a 243 would be blown to bits with an exit wound bigger than a grapefruit. The next, the roo would literally go back to feeding (apologies to Don) or hop nonchalantly away.
None of this makes me an expert, but we would shoot thousands in a year. We used whatever we felt like using from 22 lever actions to 30 cal magnums. We also accounted for hundreds of pigs per year in much the same manner and I noticed much the same inconsistent performance at times.
The one thing I would definitely say i did learn, was that using softer bullets generally made for quicker put downs, setting aside the odd aforementioned abberation in performance. I still hold to this today and that's why i favour the likes of Interlocks, Gamekings, Hotcors and such over those hard monos and so on.
I don't think there's much point in thought-experimenting bullet "failure" to the n-th degree. Sometimes crap happens.
