There was a lot of copper cased ammo before the early 45-70s that didn't seem to have that problem, Spencer 56-56 & 56-50, 58 RF, Joslyn/Peabody 50-60, 50-70, 50 Carbine/Cadet, etc. etc. I suspect that 45-70 being longer was more susceptible to extraction problems, but the main issue was verdigris and dirt from being carried in leather Fair Weather Christian belts made by company saddlers. The other issue is that unlike a Sharps, Rolling Block or most of the early single shots, with a Trapdoor you can really crank down the brechblock and chamber a round that would never seat otherwise, and once fired it is truly stuck in there.