bronko...
I don't think Muley was trying to pick a fight and I'm like you, I like my adjustable sights too. But most all custom rifles come with fixed style sights. Even some of the production guns like the Lyman Trade rifle did. The ol' timers worked up a load for their rifles for a known distance and filed their sights accordingly, from then on they had to rely on how accurately they could judge distance and use the proper holdover and judge the wind as well. Powder and lead were very valuable commodities on the frontier so they couldn't be experimenting with different charges etc. as we do. They had a load that worked well for them under most if not all situations and stuck with it.
As far as learning Tennessee elevation and Kentucky windage, they had no choice. They were either very good at it or they went hungry.
Hope that new barrel works out well for ya!
BPS