FWIW, I have 524856, cartouche date 1891.

As in most cases, the .30 Army (.30-40) cartridge was developed before the rifle was selected, so all the testing was done with modified TD rifles.

Incidentally, the officer who selected .30 for testing (and set the US Army standard for the next 80 years) was once asked why he picked that caliber. His reply was that it seemed like a nice round number. So much for ballistics, research, and so on.

Jim