I wish they would make 44-40 with rifle primer pockets again. N-SSA has had a lot of trouble with 44-40 Henrys and high primers. All it takes is a slightly high pistol primer and someone throwing cartridges down the tube on the clock, and off she goes. A few have blown magazines on the line. The current regulation is no reloading the magazine once the clock starts, which takes a lot of the fun out of repeater. (Although honestly, if you have to reload, you aren't competitive anyway.) I'll never forget having this exact conversation with Val Forgett at an N-SSA shoot. He said that he had never heard of one of his Henrys bowing a magazine, and at that very moment, one went off about 15 positions down!
Besides, black powder likes hot primers, so rifle primers should be a good thing.