RE: Three Shots to put a Bull down.
Two problems jump out, 130 gr bullet and head shot. I' ve been taught since I was a little guy that if all you have is a head shot, you don' t have any shot at all. Even though I don' t like a 270 for elk hunting because of limited range at 40yds it should work fine. Always shoot for the boiler room. Even though you' ve had experience shooting one in the heart and lungs and it ran off, thats the exception not the rule. Head shots are always iffy.
However to answer your post, these animals are extremely hard to bring down. In my opinion they are tougher than moose to drop.