I have a original Danish rolling block, that I thought had been rechambered in 45/70, and I have found since then, it is 11.3mm or 11.4 whateever. I think they used a hollow base, around 400 grains. I am sure some of you guys are more knowledgeable than I am on this so all help appreciate. By the way, the bore is about as slick as you can find, bright and shiny no pits, and rifling is still squared off on the edge.