2400 is made by Alliant, same as Unique etc. However, I've had good results with both Unique(9 - 11gr.) and 4198(about 22gr). both with Lyman 311284, 311365, and 311299 - not much to choose. Any of those will average 2 - 2 1/2" for 5 shots at 100 yards with iron sights. There's no reason H110(15 - 17gr.) shouldn't do as well. While I haven't tried it in the Krag, I've had good results in other rifles with reduced loads of H414, but usually didn't stick with them because it took so much more powder that it was much more expensive. The faster powders give useable velocity and a lot less noise/perceived recoil than the slower ones. Just be careful not to double a charge. The same designation (IMR4350 vs H4350) are not always the same. Anyway, I hope some of that helps.
Ron