Originally Posted by Hurryin' Hoosier
If I recall correctly, the 9MM Luger (9MM Parabellum) is actually a lengthened version of the 9MM Browning (9MM Short, 9MM Kurz, 9MM Corto, 9MM Scurt, .380 ACP), no?
The .380 is 9x17mm versus the 9mm Luger at 9x19mm. So in comparison the .380 is shorter than the 9mm Luger in both bullet and cartridge. The Luger came out in 1902 and the .380 in 1908. So specificity speaking the .380 is a shortened version of the 9mm Luger since it was introduced after. Now I don't know if Browning specificity had Luger's design in mind when he made his .380 round, but it would have definitely been available to him.
The .380 was designed to be a self-defense round versus the 9mm Luger that was created specificity for military applications. Both were designed to be used in a blow back systems so its logical to assume that Browning did base his .380 ACP on the 9mm Luger.
Also the 9mm Luger was designed to be a more powerful round than Luger's previous design the 7.65 Luger at 7.65 x 21mm