Early on there was a low pressure smokeless .45/70 load by both Rem and Winch using a jacketed 405gr. FN at 1,320fps, supposedly matching the 1873 mil. loading of BP with the 405gr. lead bullet. The later 1880's mil loading of 70gr. BP and 500gr. RN at 1,210fps which worked fairly well on bison in the 1800's, wasn't duplicated in a modern smokeless load.
In the 70's or early 1980's Federal came out with the first modernized smokeless loading for the .45/70 with a 300gr. Jacketed FN at something over 1,800fps that was safe in ALL .45/70 rifles including the 1873 Trapdoors. Rem. and Winch. followed suit.
These loadings should show QUITE plainly why the round didn't see popularity in Africa. I thought, wrongly it seems, that everyone knew this.
The Marlins, with their 43,000PSI max loading pressures turned the tide on the round, however Elmer Keith and others had been loading the 1886's with 53gr. of IMR3031, producing 1,830fps with the 405gr. Jacketed and cast Bullets for decades before Marlins came on the scene.