Actually, 2400 is a rifle powder, originally designed for small, intense cartridges such as the .22 Hornet. A charge of 16 grains is widely-accepted as a good choice for cast bullets of normal weight in .30-40 Krag. The following is quoted from the work of C.E. Harris:

"Sixteen Grains of #2400 Is The Universal Load . . . It is mild and accurate in any larger military case from a .30-40 Krag or .303 British up through a .30-'06 or 7.9x57, with standard-weight bullets of suitable diameter for the caliber.  This is my recommendation for anybody trying cast bullet loads for the first time in a military rifle without prior load development.    I say this because #2400 is not position sensitive, requires no fiber fillers to ensure uniform ignition, and actually groups better when you just . . . load the rifle and bang them off, rather than tipping the muzzle up to position the charge."