However, it should be noted that when Elmer was shooting his 429421 with 22 grains of 2400, that load and powder was famous for copious amounts of unburned powder ejected on each shot. I have not seen that phenomenon with modern 2400 (I don't think it is same stuff) but shoot very little of it these days.Actually, 2400 is best not used with a magnum primer. Elmer Keith put that to rest many years ago.
Don