I'm still in the Ballistics and rifling learning stages. If you check the Pedersoli repros, all of there 1874 45-70 models have the same configuration. Also, their Springfield Trapdoor 45-70, Target long range rifle has the same thing. Their Springfield mid-range is definitely different - 3 groove, 1:22 twist. I have to digest all of this yet and figure out how it all works.