Two things.
1) Lewis and Clark did have an air rifle. It was used for small game and to impress the Indians. No way could it have been considered a big bore for large game.
2) You can't compare rifles to arrows. If the bullet doesn't expand very much, it will only create a narrow wound channel. People think that, since arrow shafts are slender, it's about the same wound channel but that is not how they work. Arrows kill more by internal hemorrhaging. Those blades are rotating and slice through a lot of blood vessels. You can put a .22 bullet through an animal and it will keep going strong. An arrow from a modestly powered bow will kill it, although not on the spot.
Gene, meant no disrespect to your friend. Wish, myself, I had half as much hair as ZZ Top.