Jim: Don't shoot any loads using that early Brass! The cases have just become brittle because of time. There is no way to salvage 80 to 116 year old cartridge cases. You can clean and use the projectiles, but, nothing else. Don't test your Guardian Angel further!
.30-40 Brass may be seasonal, but it is still made. (Graf & Sons' has it). If all else fails, 303 Britishicon Brass can be fire formed to make useable Brass for a Kragicon. (Note also, early U.S. Krag ammo was mercuric primed, which is death to brass).