Vern Humphrey
Member
The .30-40 was an American version of an 8mm rimmed cartridge originally developed in Switzerland, and adapted for the Danish Krag-Jorgensen rifle. We also adopted the rifle -- in 1892. This was the first smokeless powder cartridge developed in the US (and we only modified an existing design.)
The old "two-number" system meant caliber, followed by the weight of the black powder charge in grains (there are 7,000 grains in a pound.) Sometimes a third number was added -- the weight of the bullet in grains. For example, .45-70-405, which was the .45 caliber black powder cartridge the .30-40 replaced. It held 70 grains of black powder and shot a .45 caliber, 405 grain bullet.
With smokeless powder, this system was obsolete (there being different kinds of smokless powder, with different characteristics.) The cartridge was officially the .30 US Army. But because it was loaded with about 40 grains of powder, civilians started calling it the .30-40 and the name stuck.
The old "two-number" system meant caliber, followed by the weight of the black powder charge in grains (there are 7,000 grains in a pound.) Sometimes a third number was added -- the weight of the bullet in grains. For example, .45-70-405, which was the .45 caliber black powder cartridge the .30-40 replaced. It held 70 grains of black powder and shot a .45 caliber, 405 grain bullet.
With smokeless powder, this system was obsolete (there being different kinds of smokless powder, with different characteristics.) The cartridge was officially the .30 US Army. But because it was loaded with about 40 grains of powder, civilians started calling it the .30-40 and the name stuck.