High Quality Content by WIKIPEDIA articles! The .45-70 rifle cartridge, also known as .45-70 Government, was developed at the U.S. Army`s Springfield Armory for use in the Springfield Model 1873, which is known to collectors as the "Trapdoor Springfield." The new cartridge was a replacement for the stop-gap .50-70 Government cartridge which had been adopted in 1866, one year after the end of the American Civil War.