I don't know about about Jack O'Connor being a great hunter. Seems to me he had good guides, which allowed him to shoot a lot of game around the world.

His average # of shots to kill a Canadian Moose was reported in Gun Digest as being 3.8. As most moose shooting is done at close range, usually between 15 and 100yards, you might wonder why he "averaged" 3.8 shots?

Now, his wife Eleanor, used just 29 shots, to kill 28 head of African game. She used her favourite 7mm Mauser, but it wasn't loaded with 130 or 140gr, bullets. Seems to me, she liked 160gr. Nosler Partitions, iirc.

My buddy's wife killed several African Antelope with her .270, using 130gr. TTSX's - including an almost record Kudu. All one shot kills, which she does each year on deer, bear(a huge one last fall) and moose, same rifle, same loads.