54 roundballs are simply deadly on deer.
They are, but for deer-only, I shoot a .45 TC Seneca. I don't need a .54 for deer, I want it for elk, and for elk, I want more than 230 grains of lead. (I don't care how many mountain men were successful with it.) As the bullet situation stands now, a person is better off hunting elk with a .50 with available conicals than a .54 that's ever more limited to round balls. .54 is going the way of the .58. (I like a .58 with PRB, though .. 289 grains .. an additional 60 over what the .54 provides .. is a useful step up.)
Tom