Actually, most modern cartridges are redesigns of the 303 British. European spies were everywhere! US ones as well. The 30-06, contrary to popular belief, had nothing to do with Peter Paul's Mauser, or the cartridges that were fired from them. Espionage was rampant.
Even the use of wood as a rifle stock was copied from the Lee Metford/Enfield designs. The Prussians weren't having much success using bratwurst as stock material, and took the British lead by using wood.
The 30-06 - an elongated rimless 303 British. The 308 - a US copy of a rimless 303 British. The Mauser cartridge family (all variants) German copies of a stretched rimless 303 British. The 22 LR - a really, really small 303 British. The 375 H&H - a bigger 303 British. etc.
