I had a .40-70bn once. It was a roller and it also came with two boxes of ammo. The shells where most unusual. The base was threaded iron that screwed into a brass upper part.
This caliber was a very tough one to get to shoot worth a hoot even worth the original factory rounds and reloads. But this was back in the 50's when I had that rifle and I was still sifting out blasting powder we had out in the machine shed to reload the cartridges

But I would like to have another one in that caliber.
Kurt