Two home gunsmiths, Chapaev and Voland, have been working on converting two Mosin Nagant rifles to use the .45-70 cartridge. Their almost completed rifles have a 3+1 capacity, 16.25″ barrels and fiber optic sights.
It was no easy task with a lot of modifications required. The pair extensively documented the process on their blog Pharmory.
I think Captain Mosin and Mr Nagant would approve.