30 Army , 30-40 Krag
Military Cartridge Stock Section
The 30 Army is a small -bore rimmed cartridge introduced into the U.S. Military in 1892 for the
(Krag-Jorgensen) Bolt Action Rifle which replaced the 45-70 Cartridge.
The nick name 30-40 Krag was given to the .30 Army as it was used in the Krag rifle and was loaded
40 grains of smokeless powder, and was a  30 caliber, so the nick-name 30-40 Krag stuck.
It was replaced in 1903 by the 30-03 or 1903 Government, before the 30-06 replace the 30-03 in 1906.  
It is still used today and a good hunting rifle cartridge.