One of the most popular NRA events is the long distance black powder competition at 800, 900 and 1,000 yards. Very accurate shooting at those distances using .45-70s and 50-80s and some other rounds.
Another competition was so tough that they moved the targets out to 1238 yards. A woman won the competition.
Black powder rifles are very capable.
I shoot 45-70, I have used Hornady red tipped cartridges, they increase the fps, by about 250fps, according to the manufacturer, most rounds for lever action are flatnose, still 1300fps but no way accurate. I have a lever action Marlin and there is no way in hell that 45-70 is a long range cartridge.