my 2cents on ammo and rifles....
In 2004 I practiced all summer with my Rem 700 for my ( first ever big game) Caribou hunt in northern Canada mostly using Rem express rounds. For the hunt I bought a box of Rem Scirocco bonded, fired 3 at the range and they grouped sub 1” at 200 yards so I was all set. The express rounds were flying around a little more but I was confident I could hit any caribou sized target at 200 yards with them as well.
So I arrived in Montreal at 12 mid night with plans to board the plane for the hunt at 7am the next morning. Unfortunately at the baggage claim the rifle never came out. I managed to learn from the French speaking baggage handler that my rifle would be on the next plane in at 10am the next morning.
There was only 1 plane to Caniapiscau and I had to get on it so my rifle was left in the care of United.
When I got to Caniapiscau the guide service loaned me a Win model 70 with a random scope and a box of random 30’06 ammunition that he had laying around. When I got to camp I fired 2 rounds and it seemed to shoot straight enough at 80yrds so I was off.. Later that afternoon I shot my first Caribou at about 170 yards, It keeled right over on the spot. It was on my second trigger pull as the first one I had left the safety on and literally hauled back on the trigger. I flipped the safety off and tried to keep my heart in my chest as i settled down and went in to the 3 breaths, let it half out and squeeze drill.
So long story short, today’s high quality rifles, and high quality ammunition will get the job done. All my fancy Scirocco ammo didn't matter at all sitting in Montreal airport... I personally think what really makes the difference when everything is on the line is the training and practice of the guy pulling the trigger.
Its not an exact answer to your question but maybe it is...
PS my buddy’s rifle was in the same case as mine, so he ended up with a borrowed older Rem 700 .270 with an even more random scope and ammo and managed to easily shoot 2 caribou as well.
PSS a week later I returned to the Montreal airport and retrieved my rifle, the good news was I didn’t have to pay the CN$100 import fee into Canada as it stayed in the airline locker the whole time….