I have had about a 10% success rate on tipping moose over with the first shot. A brain shot will both kill and drop a moose instantly, obviously. Anything else is comes with some uncertainty. (I did not say a head shot because simply shooting a moose in the head leaves A LOT of room for missing their brain - and neither dropping, stopping, nor wounding them in a manner which is rapidly lethal.) I avoid headshots except from a feet feet when dispatching them - and, avoiding an antler splaying shot, I sometimes don't successfully kill them instantly even then.
I have had three instant drops over the years. The first moose tipped right over with a soft point shot through the lungs from less than 50 yards. I don't remember how close to the heart the bullet went. It was my first big game kill and I don't remember doing any forensic analysis. I have since had a moose tip right over, not very dead, when I broke both shoulders through the humerus/scapula joints and another which disappeared from view during recoil from what I could only determine must have been the proverbial "shock". (There was no extensive bleeding nor were any bones broken, but the bullet passed near both the kidneys and the spine which dropped the animal so fast that his antlers speared the ground and his nose was skyward. It took me several minutes to find him after looking where I thought he would have gone in a wounded state, but then finally finding him right where I had last seen him. In other words, he may have lived in the awkward position as he fell and died from suffocation or a "broken neck" perhaps.)
But, generally, I simply shoot moose through the lungs and that has been a quickly lethal and very reliable way to get the animal killed. Sometimes they've moved a few yards, sometimes they simply stand around. Breaking one shoulder (or even a hind leg) may not drop them or even stop them. Spine shots have alway worked well too - at least as secondary shots. I've never aimed to hit the spine as a primary (first) shot.
While I am a dedicated "lung"er, a few things I think I've learned include these:
* Moose are not difficult to kill
* Moose make excellent bullet traps; they can stop some of the best bullets you can send their way. IOW, they are bigger and tougher than most other NA animals.
* The only really reliable way to drop a moose instantly is with a CNS shot, but CNS shots are often not simple nor is a "near miss" a reliable killing shot.
* Moose have a very large lethal killing zone: the lungs. And, short of a watery death hole possibility, it is otherwise a good place to poke them. (That's why I am a dedicated "lung"er.)
But based on why I've seen so many moose die from lung shots, it appears that they either drown in the own blood or die from bleeding out (loss of blood pressure). Either will take some time, though bigger blood-letting holes probably hasten things. I would imagine that is the answer to the question about light BT type bullets and their effects.
