I dug out an old book i've been meaning to read, The Journals of Lewis and Clark.This edition edited by John Bakeless. It must have been something to see this country then.
The air rifle they carried was WAY ahead of it's time: https://en.wikipedia.org/wiki/Girandoni_Air_Rifle
They only lost one man and it was to disease or illness. It is believed he had appendicitis, at that time no matter where that man would have been he would have died. There is no way he could have been opperated on.