My first rifle was a Sharon Trade Rifle, percussion, .50. I added a .54 barrel but never did go elk hunting. I added a .62 smoothbore that shoots low with a round ball and it's too stout at 1" straight octagon to bend by hand. It's OK for squirrels and bunnies. My best hunting buddy used to tease me unmercifully about carrying a quiver full of barrels and being loaded for squirrel when a 10 point buck shows up. "Urrr- Mr. 10-Point, would you mind standing there for a minute while I change barrels then load this one?"
It was a pain to make 2 identical tangs drilled etc to fit the inlet, to have the drums line up perfectly, lugs lined up perfectly, etc. Would be the same with a flintlock.
But I enjoyed doing it even if the extra barrels do not see much use. The old .50 percussion works for rainy days or to lend to a newbie.