You never read the Journals of Lewis and Clark? Or "Undaunted Courage?"
They ran into some area's where the Elk and Deer were thick and basically unafraid of man at that time. Most of the way, not all of it, but there was an abundance of game. It wasn't until we started shooting them, that they woke up and saw man as a threat. It only got worse as more people went west and the distances between humans and animals grew more and more.
Whoa, Swampy, you are treating the arrival of Lewis and Clark as though they were the first humans to arrive in the west! The elk, deer and buff had been hunted hard by native americans for centuries before L&C showed up. I expect the big game of the west was terrified of humans long before a white man arrived. On top of that, there were of french trappers and traders in the west long before L&C showed up.
Oh they took game with roundballs but eventually they needed something that shot further as distances grew.
They were whacking all the game of the west handily with the rb long before their was any other option. After the end of the mountain man era those who remained in the west continued to arm themselves with round ball loaded ml guns. Distances at which game was taken would not have grown, IMO. The change from rb to conical came with the arrival of the breech loading suppository gun. And, of course many switched to them if they could afford it. Especiallyn if they were proffessional buff hunters. It was not the ability to shoot that much further that was attractive though; it was the ability to quickly reload. It was all about practicality and economics! Well into the cartridge era settlers headed for the west were arming themselves with "trade rifles" that loaded a patched ball.
We always seem to talk about the fur trade era as something that took place between L&C and the mid to late forties. While the heyday of the western beaver trade died at that time, the fur trade continued for many years and actually began with the first arrivals of white settlers on the continent. The American mountain man era was only a very small slice of the North American fur trade. I like to think of the American mountain man era as being book ended by John Colter seeking and gaining permission to leave the L&C expedition to seek his fortune and up to the time that Meek decided that Oregon might be more prosperous than the beaver trade.