From what I understand, the black powder cartridge competition shooting is done with vintage type single shot rifles, usually in large bore calibers, typically 40 caliber or larger. When I was reading a lot about it, the 45-70 and 45-90 were two of the most popular calibers. There were a fair amount of people who competed with 40 caliber rifles also. The most popular types of rifles were the Sharps type and the rolling block type actions, with several other types being used as well. I haven't kept up with it for the last year or 2.